Tools

242 free tools across 12 categories. No signup, no ads — everything runs in your browser.

Tutorials

Step-by-step guides that solve one problem with one of these tools.

All 20 tool tutorials →

AI & LLMs

LLM Tokenizer Visualizer
See the real BPE tokens, token IDs, and character ratio for pasted text.
MCP Config Generator
Build Cursor and Claude MCP configurations for stdio, SSE, and HTTP servers.
AGENTS.md Generator
Generate concise AGENTS.md or CLAUDE.md project instructions from a questionnaire.
Inference Cost Calculator
Estimate your monthly LLM inference bill and compare models across OpenAI, Anthropic, Google, and more.
Token Counter & Prompt Cost
Paste a prompt, get an approximate token count and what it costs as input across every major LLM.
AI Subscription vs API
Is ChatGPT Plus or Claude Pro worth it vs paying per token? Find your break-even point.
Context Window Fit Checker
Paste your prompt stack and see which LLMs fit — with a bar showing how much of each model’s context window you use.
Prompt Cost Diff
Compare two prompt variants: token delta and dollar savings per model, per call and per month.
Embeddings Cost Estimator
Estimate embedding API cost, chunk counts, vector storage size, and rough monthly bills for your corpus.
LLM Latency Calculator
Estimate LLM response time by output length — compare time to first token and total wait across models.
AI Agent Cost Visualizer
See how multi-step agent runs get expensive as context grows each step — per-step cost table with monthly totals.
Model Tier Quiz
Seven questions to pick budget, workhorse, or flagship LLM tier — with honest advice to start cheap.
Fine-Tuning vs RAG vs Prompting
Seven questions to pick fine-tuning, RAG, or prompt engineering — with honest cost ranges and anti-recommendations.
System Prompt Linter
Lint system prompts in your browser: contradictions, vague wording, missing format spec, wasted tokens. Rule-based, not AI.
Sample App Idea Generator
Get a web app idea to build for practice or a tutorial: curated ideas with features, or generate a fresh one with AI.
GPU / VRAM Calculator for Local LLMs
Estimate VRAM for quantized weights plus KV cache, and see which RTX cards and Apple Silicon tiers fit your model.
Local LLM vs API Break-Even
Buy a GPU or pay per token? Amortized hardware + electricity vs API pricing, with the break-even point in months.
RAG Chunk Size Calculator
Chunk count, embedding cost, vector storage size, and whether top-k retrieved chunks actually fit your context window.
llms.txt Generator
Generate an llms.txt file for your site — a curated markdown index that helps LLMs and AI crawlers understand your content.
JSON Repair
Repair invalid JSON from an LLM in your browser. Fixes code fences, trailing commas, single quotes, comments, and cut-off brackets, and lists each fix.
Cosine Similarity Calculator
Paste two JSON arrays and compare them in the browser. You get cosine similarity, the dot product, magnitudes, and Euclidean and Manhattan distances.
Token Rate Calculator
Turn RPM and TPM limits into requests you can send per minute. You type the limits and the tokens per request. The page does not look up a provider rate card.

JavaScript & TypeScript

JSON Tree Visualizer
Explore JSON as a searchable, collapsible tree with paths, details, and statistics.
Regex Tester & Explainer
Test regular expressions with live match highlighting and a plain-English breakdown of the pattern.
JSON Formatter & Validator
Validate, pretty-print, and minify JSON with clear error messages. Runs entirely in your browser.
JWT Decoder
Decode JSON Web Tokens client-side: header, payload, claims explained, and expiry status. Nothing leaves your browser.
JSON to TypeScript
Paste JSON and generate TypeScript interfaces with nested types and optional keys — entirely in your browser.
JS Date Formatter
Pick locale and date parts, see live Intl output, and copy snippets for Intl, date-fns, or Temporal.
JS Equality Explorer
Compare two values with ==, ===, and Object.is — see the coercion steps and classic gotcha presets.
Number Format Playground
Tweak Intl.NumberFormat options for locale, currency, and notation — live output plus a copy-paste snippet.
String Case Converter
Convert one string to camelCase, snake_case, kebab-case, and six more cases with copy buttons per row.
URL Parser & Builder
Paste a URL to see every part labeled — protocol, host, path, query params, hash. Edit any piece and copy the result.
Encode / Decode
Encode or decode Base64, URL components, and HTML entities in your browser. Unicode-safe Base64 included.
ID Generator
Generate UUID v4, nanoid, or ULID strings in your browser — with collision-probability math for nanoid.
Event Loop Visualizer
Step through JavaScript event loop examples: call stack, microtask queue, macrotask queue, and console output.
tsconfig.json Generator
Answer six questions and get a commented tsconfig.json for TypeScript 5.x — browser, Node, or library setups.
String Escape / Unescape
Escape and unescape JavaScript strings, JSON strings, hex bytes, and Unicode sequences — with a swap button.
String Inspector
Why .length lies: UTF-16 units vs code points vs graphemes vs UTF-8 bytes, plus hidden-character detection and clean copy.
Number Base Converter
Live conversion between binary, octal, decimal, and hex — BigInt-backed, with two’s complement and a nibble explainer.
Array Method Chooser
Pick a goal, get the right array method with a snippet, mutating badges, gotchas, and a searchable full reference.
Promise Combinator Chooser
Promise.all vs allSettled vs race vs any — answer three questions, then watch simulated promises settle on a timeline.
Date Duration Calculator
Diff two dates, add or subtract durations, or count down — with business days and vanilla/date-fns/Temporal snippets.
Sort Comparator Builder
Build multi-key JS sort comparators visually, preview on your JSON, and copy clean compare functions.
UUID Inspector
Paste a UUID or ULID: version, variant, embedded timestamps decoded — and why v7 is the DB-friendly choice.
JWT Generator & Signer
Build and sign HS256 JWTs with Web Crypto, or verify a token against a secret. Secrets never leave your browser.
JSON to Zod Schema
Paste JSON, get a Zod v4 schema — nested objects, unions, nullable fields, optional email and datetime detection.
JSON Schema Validator
Validate a JSON document against a JSON Schema in your browser — every error with its path, keyword, and message.
JSON to JSON Schema Generator
Paste sample JSON and get a JSON Schema with required keys and formats, plus a strict mode for OpenAI Structured Outputs.
TypeScript Utility Types Explorer
Partial, Pick, Omit, Record, ReturnType and friends — before/after examples, when to use each, and how they work.
JSONPath Tester
Test JSONPath expressions against your JSON — wildcards, recursive descent, slices, and filters, with matched paths shown.
Keyboard Event Codes
Press any key and see event.key, event.code, and modifiers live — with a reference table and copy-ready JS snippets.
ESLint Flat Config Generator
Answer a few questions, get a commented eslint.config.js for JS or TS, React, Vue, or Astro — plus the exact install command.
Vite Config Generator
Generate a commented vite.config.ts with path aliases, dev proxy, build options, and Vitest setup for your framework.
JSON Diff
Compare two JSON values in your browser and see every added, removed, changed, or moved field with its path. Key order is ignored.
OpenAPI to TypeScript
Paste an OpenAPI 3.0 or 3.1 document and get TypeScript interfaces for schemas, path and query parameters, and JSON request and response bodies.
URL-encoded Form to JSON
Convert an application/x-www-form-urlencoded body to JSON and back in the browser. Repeated keys become arrays, and a plus sign is a space.
Unicode Normalization
Convert a string to NFC, NFD, NFKC, or NFKD and list the code points before and after. The string stays in the browser and is not put in the URL.
JSON Key Sorter
Sort JSON object keys in the browser. Arrays keep their order. Case-sensitive sort uses UTF-16 code units. The JSON is not stored in the URL.

Tailwind CSS

Tailwind Page Layout Generator
Generate responsive dashboard, marketing, split-screen, holy-grail, and centered app layouts.
Tailwind Grid Builder
Build responsive grids visually and copy the Tailwind classes and HTML.
Tailwind Flexbox Builder
Configure direction, wrapping, alignment, justification, and gaps with a live preview.
Tailwind Container Query Builder
Build and preview responsive components using @container and Tailwind container variants.
Tailwind v4 Theme Generator
Create CSS-first @theme tokens for colors, fonts, spacing, and breakpoints.
Tailwind Button Generator
Design accessible buttons and copy Tailwind classes with hover, focus, and disabled states.
Tailwind Form Generator
Generate accessible Tailwind form fields with labels, help text, errors, and focus styles.
Tailwind Card Generator
Build cards and responsive card grids with optional images, headers, bodies, and footers.
Tailwind Table Generator
Create responsive tables with stripes, borders, compact spacing, and sticky headers.
Tailwind to CSS Converter
Translate common Tailwind utilities into CSS and flag unsupported classes.
Tailwind v3 to v4 Migration Helper
Find renamed utilities and CSS configuration patterns that need updating for Tailwind v4.
Tailwind Class Sorter
Sort and deduplicate Tailwind classes while spotting obvious utility conflicts.
Tailwind Class Conflict Debugger
See which utilities target the same CSS property and which class wins.
Tailwind Dark Mode Helper
Add suggested dark: variants to common light-mode classes and preview the result.
Tailwind Color Picker
Browse the Tailwind v4 palette or find the nearest utility for any hex color.
Tailwind Shadow Generator
Build layered shadows and export arbitrary classes or Tailwind v4 theme tokens.
Tailwind Typography Scale
Generate a modular type scale with Tailwind v4 font-size and line-height tokens.
Tailwind Spacing Scale
Look up spacing utilities visually and generate a custom Tailwind v4 spacing scale.
Tailwind Breakpoint Tester
Test viewport widths and see which responsive Tailwind variants are active.
Interactive Tailwind Cheat Sheet
Search and filter a practical reference of common Tailwind v4 utilities.

CSS & HTML

Favicon & App Icon Generator
Turn an image, emoji, or text into PNG icons, a favicon.ico file, and manifest markup.
CSS Clip-Path Generator
Draw polygons or configure circle, ellipse, and inset shapes with a live CSS preview.
Open Graph Image Generator
Create and download a 1200×630 social preview image entirely in your browser.
CSS Filter Generator
Build filter and backdrop-filter effects using sliders, presets, and a live preview.
Scroll-Driven Animation Generator
Generate CSS view and scroll timeline animations with live reveal, progress, and parallax demos.
JSON-LD Generator
Generate validated structured data for articles, products, courses, books, FAQs, and organizations.
Flexbox Playground
Toggle flex container and item properties, see the layout update live, and copy the generated CSS.
CSS Grid Generator
Paint named grid areas on a clickable grid, preview the layout, and copy grid-template-areas CSS plus HTML.
Box Shadow & Border Radius
Stack up to three box shadows, tweak border-radius per corner, preview the result, and copy the CSS.
Color Converter & Contrast
Convert CSS colors between hex, rgb, hsl, and oklch, then check WCAG 2.1 contrast ratios for text on a background.
CSS Units Converter
Convert between px, rem, em, %, and pt with a configurable root font size, plus a quick px→rem reference table.
clamp() Calculator
Compute fluid typography clamp() from min/max font sizes and viewport widths — with the slope math shown.
CSS Specificity Calculator
Paste CSS selectors and get the (a, b, c) specificity triple for each — ranked so you can see which rule wins.
Meta Tags Generator
Generate title, description, canonical, Open Graph, and Twitter Card tags — with SERP and social card previews.
Favicon Checklist
Pick platforms to support and get a modern favicon file checklist plus copy-paste link tags and manifest snippet.
HTML Entity Lookup
Search common HTML entities by name, number, or character — copy named or numeric forms, or encode arbitrary text.
SVG to CSS Data URI
Encode SVG markup into CSS-ready data URIs — URL-encoded vs base64 byte counts, background-image and mask snippets.
Easing Function Previewer
Compare CSS timing functions side by side with live animations and cubic-bezier curve plots — copy the one that feels right.
CSS Gradient Generator
Build linear, radial, and conic gradients with a stops editor and presets — copy clean, ready-to-paste CSS.
srcset & sizes Generator
Generate responsive srcset, sizes, and <picture> markup from a filename pattern — see which file the browser would pick.
CSS Selector Tester
Test any selector against pasted HTML — match list, source highlighting, and specificity, all in your browser.
Aspect Ratio Calculator
Convert dimensions to ratios, lock a ratio while resizing, and compute contain/cover letterbox and crop math.
CSS Keyframes Generator
Build @keyframes animations step by step with a live preview and a prefers-reduced-motion wrapper included.
CSS to Tailwind Converter
Paste CSS declarations and get the matching Tailwind v4 utility classes — spacing-scale snapping and arbitrary-value fallbacks.
Color Palette Scale Generator
Turn one brand color into a full 50–950 scale using OKLCH — export as CSS variables, a Tailwind @theme block, or JSON.
Media & Container Query Generator
Build media query breakpoint sets and @container queries — mobile-first skeletons, preference queries, copy-ready CSS.
Image Format Chooser
JPEG, PNG, WebP, AVIF, or SVG? Answer a few questions and get the right format with a fallback <picture> snippet.
SVG Optimizer
Optimize SVGs with SVGO right in your browser — before/after sizes, visual preview, and your files never get uploaded.
PWA Web App Manifest Generator
Generate a manifest.json for your PWA with icons, display mode, and theme colors — plus the link tags and an install checklist.

Git

Git Hooks Generator
Generate plain Git hooks or Husky and lint-staged setup for pre-commit and pre-push checks.
Dependabot & Renovate Config Generator
Create dependency update configuration with schedules, groups, labels, and reviewers.
Git Command Finder
Search or browse 75+ Git commands by goal — undo commits, branches, remotes, stash — with caution notes for destructive ops.
.gitignore Generator
Check your stacks (Node, macOS, VS Code, Python, Astro, env files) and copy a commented .gitignore.
Git Recovery Tool
Answer what went wrong — wrong branch, lost commits, committed secrets — and get step-by-step recovery commands.
Commit Message Builder
Build Conventional Commits messages with live validation, breaking-change footers, and copy-ready one-liners.
Semver Advisor
Pick what changed for the correct semver bump (including 0.x rules), plus plain-English explanations for ^ and ~ ranges.
Git Branch & Rebase Visualizer
Step through merge, fast-forward, rebase, and cherry-pick scenarios on an animated commit graph — see what each command really does.

Node.js & Backend

Chmod Calculator
Convert Unix permissions between rwx checkboxes, octal (755), and ls -l notation — with common presets.
HTTP Status Codes
Search HTTP status codes 1xx–5xx with plain-English meanings and practical when-to-use notes.
.env Converter
Convert .env files to JSON or YAML and back, in your browser — comments, quotes, and multiline values handled.
.env Diff
Compare a .env file with .env.example in your browser. Find missing keys, extra keys, empty values, duplicate keys, and broken quotes.
Route to curl
Build curl, fetch(), and httpie commands from method, URL, params, headers, and JSON body — with copy button.
Bcrypt / Argon2 Cost Calculator
Estimate bcrypt and argon2 hash times and rough offline crack timelines — educational, not a benchmark.
npm Package Weight
Compare min+gzip bundle sizes for ~40 common npm packages and see lighter alternatives.
Node.js Version Features
Pick a Node LTS version to see its features, or pick a feature to see which version you need.
cURL to Code
Paste a curl command and get fetch(), Node.js, or Python requests code — headers, auth, form data, and JSON bodies handled.
Hash Generator
SHA-1/256/384/512 and MD5 digests plus HMAC signing, from text or files — hex or Base64, all in your browser.
Webhook Signature Verifier
Check Stripe, GitHub, Slack, Shopify, Paddle and Standard Webhooks signatures, and see why a valid webhook fails verification.
tar / find / rsync Command Builder
Describe what you want in plain English and get the exact tar, find, or rsync command with every flag explained.
Glob Pattern Tester
Test glob patterns against a file list with gitignore or minimatch semantics — see exactly what matches and why.
Byte Size Converter
KB vs KiB conversions done right, plus transfer times at common connection speeds — no more 1000 vs 1024 confusion.
Exponential Backoff Calculator
List the wait before each retry from a base delay, a multiplier, and a cap. Compare no jitter with full, equal, and decorrelated jitter.
Basic Auth Header
Build or decode an HTTP Basic Authorization header in the browser. UTF-8 mode uses NFC, then UTF-8, then Base64. ISO-8859-1 is the legacy option.
Secret Key Generator
Generate a random secret key in the browser with the Web Crypto API. Pick 16 to 64 bytes and copy hex, Base64, or Base64url. The key is never stored in the URL.
Semver Range Calculator
Check if a version satisfies an npm semver range, and test a list of versions. The page shows the expanded range, including the -0 prerelease bound.

Databases

Postgres EXPLAIN Visualizer
Turn EXPLAIN FORMAT JSON into a readable query-plan tree with cost and timing hotspots.
Database Chooser
Six questions to pick SQLite vs Postgres vs KV vs columnar — with honest anti-recommendations and typical pricing.
SQL Formatter
Pretty-print SQL in your browser — keyword casing, clause breaks, indentation, or compact minify.
Schema Converter
Convert a CREATE TABLE to Prisma and Drizzle — or paste Prisma or Drizzle and get SQL back.
Database Index Advisor
Describe your query pattern and get a suggested CREATE INDEX with plain-English reasoning. Verify with EXPLAIN.
Connection String Builder
Build or parse Postgres, MySQL, and SQLite connection strings. Passwords stay in your browser.
Postgres vs SQLite vs MySQL
Head-to-head comparison of the three classic relational engines, plus a four-question helper with honest tradeoffs.
CSV to SQL Converter
Paste CSV, get CREATE TABLE and INSERT statements — type inference, dialect quoting, batching, and NULL handling.

React, Next.js, Astro & AHA

React Hook Chooser
Pick the right React hook for your goal — with snippets and honest "you probably don’t need useEffect" notes.
React Key & Re-render Quiz
Ten questions on React keys, reconciliation, and memo — instant feedback, code snippets, shareable score.
Next.js Rendering Chooser
Six questions to choose static, ISR, SSR, or client rendering in Next.js — with the exact code convention to use.
Astro Islands Cost Visualizer
Stack simulated Astro islands by framework and client:* directive — see approximate JS shipped vs a 100 KB budget.
htmx Attribute Builder
Build complete hx-* attributes from a form — live HTML output, plain-English readback, and copy button.
Alpine.js Cheatsheet
Alpine core directives with snippets and live mini-demos — this page is built with Alpine itself.

Web Platform & Networking

HAR File Analyzer
Inspect request timing, transfer sizes, domains, caching, and slow resources without uploading the HAR.
TOTP / 2FA Generator
Generate and debug time-based one-time passwords locally with an otpauth URI and QR code.
Passkey Flow Visualizer
Step through WebAuthn registration and authentication across the browser, server, and authenticator.
Authentication Strategy Chooser
Compare sessions, JWT, OAuth, passkeys, and magic links for your application.
Web Storage Chooser
Choose between cookies, localStorage, IndexedDB, Cache API, and OPFS with security guidance.
Cache-Control Builder
Build Cache-Control headers for static assets, HTML, APIs, or private pages — with plain-English browser vs CDN readback.
CORS Debugger
Describe a cross-origin request and see simple vs preflight, the required response headers, and fixes for classic errors.
CSP Generator
Compose a Content-Security-Policy header with presets, per-directive explanations, and warnings on unsafe-inline.
DNS Record Explainer
DNS record reference (A, MX, TXT, and more) plus a helper for pointing domains, email setup, and anti-spoofing.
CIDR Calculator
IPv4 CIDR and netmask calculator with network/host breakdown, binary view, and a prefix finder for N hosts.
WebSocket vs SSE vs Polling
Six questions to pick WebSocket, SSE, or HTTP polling — with a comparison table and anti-recommendations for serverless.
Redirects Simulator
Paste _redirects rules, test paths, and see first-match results with splat substitution and rule-order warnings.
Cron Builder & Explainer
Build or paste a cron expression, get a plain-English explanation, and see the next 5 run times in your timezone.
Timestamp Converter
Unix timestamp to date and back — local, UTC, and any timezone, with a live clock and JS snippets.
HTTP Response Headers Explainer
Paste response headers and get each one explained — plus warnings for missing security headers like HSTS and CSP.
Cookie Inspector & Set-Cookie Builder
Paste a Cookie or Set-Cookie header to inspect it, or build a Set-Cookie line with SameSite, HttpOnly, Secure, and Partitioned — all in the browser.
Security Headers Starter
Generate a starter set of HSTS, nosniff, Referrer-Policy, Permissions-Policy, framing, COOP, and CORP headers — raw, nginx, or Cloudflare format.
ETag & Conditional Request Playground
Generate ETags, set If-None-Match / If-Modified-Since, and see whether the server should answer 200 or 304.
Content Negotiation Helper
Paste an Accept header, list what your server offers, and see which MIME type wins — plus Accept-Language and Accept-Encoding.
Redirect Status Chooser
Permanent or temporary? Keep the method or switch to GET? Pick 301, 302, 303, 307, or 308 with a sample Location response.
robots.txt Generator & Tester
Build robots.txt rules with AI-crawler presets, then test any path and user-agent against them before you deploy.
SPF / DKIM / DMARC Generator
Generate and explain email authentication DNS records — get your newsletter out of the spam folder.
sitemap.xml Generator
Paste your URLs and get a valid sitemap.xml — lastmod, changefreq, priority, dedupe, and sitemap index support.
User-Agent Parser
Paste a User-Agent string and see browser, engine, OS, device type, and bots detected — with honest caveats about UA lies.
MIME Type Lookup
Extension to MIME type and back — 150+ entries with Content-Type examples, charset notes, and gotchas.
security.txt Generator
Generate a /.well-known/security.txt per RFC 9116 — contact, expires, policy, and validation warnings included.
OAuth 2.0 / PKCE Flow Visualizer
Step through the Authorization Code + PKCE flow, then generate a real code_verifier and S256 challenge with Web Crypto.
Subresource Integrity Generator
Hash a file or text in your browser and copy a Subresource Integrity value for a script or stylesheet. SHA-256, SHA-384, and SHA-512.
SSE Frame Parser
Paste a finished text/event-stream body and list each event name, id, and data. The split follows the HTML Standard. A block with no blank line is dropped.

Hosting & Deployment

Docker Run to Compose Converter
Convert common docker run flags, volumes, ports, and environment variables into Compose YAML.
Do You Need Kubernetes?
Seven honest questions about your team, services, and traffic — verdict tiers from "No" to "Yes, you have K8s problems".
Scaling Strategy Helper
What’s actually slow, is it stateful, how spiky is traffic — one primary scaling strategy with honest anti-recommendations.
VPS Sizing Estimator
App type and daily visitors in, recommended server tier out — with the req/s and memory-budget math shown.
Uptime / SLA Calculator
Turn an SLA percentage into allowed downtime per day/month/year, and see what chaining dependencies does to real availability.
nginx Config Generator
Generate nginx server blocks for static sites, SPAs, and Node.js reverse proxies — HTTPS with certbot, gzip, cache headers.
Docker Compose Generator
Generate a compose.yaml for your Node.js, Astro, or Next.js app with Postgres, MySQL, Redis — healthchecks wired correctly.
systemd Service Generator
Generate a systemd unit file to run a Node.js app as a Linux service — restart policy, boot, memory limits, hardening.
GitHub Actions Deploy Generator
Complete deploy.yml for Cloudflare Pages, Fly.io, VPS over SSH, or npm publish — plus the exact secrets to set.
SSH Hardening Checklist
Interactive SSH server hardening checklist with a live sshd_config generator — keys only, fail2ban, safe restart commands.
Container Base Image Sizes
Compare Docker base images — alpine, slim, distroless, scratch — by pull size, shell, and libc, with a 3-question picker.
CI Build Minutes Cost Calculator
Builds per day × duration → monthly CI minutes and estimated bills on GitHub Actions, GitLab CI, and CircleCI.
Production Deploy Checklist
Pre-launch checklist tailored to your stack and platform — security, backups, DNS cutover, rollback — with shareable progress.
Cloudflare Storage Chooser
Five questions to pick Cloudflare KV, D1, R2, or Durable Objects — with anti-recommendations and a comparison table.
Workers Cost Estimator
Estimate monthly Cloudflare Workers, KV, D1, R2, and Durable Objects cost with plan allowances subtracted.
Bandwidth Calculator
Page views × page weight × cache hit rate → monthly bandwidth and what it costs on the major static hosts.
Free Tier Finder
What can you run for exactly $0? Every genuinely free tier from Cloudflare, Vercel, AWS, Fly.io, and Railway, filtered by what your app needs.
Caddyfile Generator
Generate a Caddyfile for static sites, SPAs, and reverse proxies — automatic HTTPS, compression, security headers.

Business & Writing

SaaS MRR Calculator
Project SaaS MRR over 24 months from traffic, trial conversion, churn, and visitor growth — with steady-state estimate.
Freelance Rate Calculator
Work out the hourly and day rate you need after tax, overhead, and business costs — with realistic personas.
Rate Converter
Convert between hourly, day, weekly, monthly retainer, and project rates — with retainer discount math.
Salary to Freelance
What freelance revenue do you need to match an employee salary? Country presets, benefits, bench time — ballpark only.
Product Pricing Calculator
Test a price change with elasticity presets; see projected revenue, break-even drop-off, and a price-range table.
Launch Revenue Estimator
Estimate course or ebook launch revenue from list size, email funnel rates, price, and launch sequence style.
Payment Platform Fees
Compare net revenue on Paddle, Stripe, Gumroad, Polar, and Lemon Squeezy for your price and monthly volume.
Newsletter Growth Projector
Project newsletter subscribers over 24 months from daily signups and churn — with 1k/10k milestone timing.
Sponsorship Rate Calculator
Estimate ad and sponsorship rates for your blog or newsletter from traffic, niche, and placement — with the CPM math shown.
SEO Title Generator
Turn a blog topic into SEO title ideas, a URL slug, and a meta description skeleton — rule-based templates, no AI.
Word Count Goals Planner
Plan blog posts, handbooks, or books: sessions needed, finish date, and week-by-week milestones from your writing pace.
Reading Time Analyzer
Paste text for word count, reading time, speaking time, and sentence stats. Your text never leaves the browser.
Slug & Headline Case Converter
Slugify any headline for URLs and convert between title case, sentence case, and more — AP and Chicago styles included.
Character Limit Checker
Check your text against SERP title, meta description, tweet, Open Graph, and email subject limits — all in one view.
Time Zone Meeting Planner
Find meeting times that work across cities with a color-coded overlap grid — working hours, early, late, or asleep.
Churn / LTV Calculator
Customer lifetime value from ARPU and churn, CAC payback months, and what halving churn does to your revenue.
Invoice Generator
Build a clean, print-friendly invoice in the browser and save it as PDF — no signup, nothing uploaded anywhere.
Project Estimate Calculator
Break work into tasks, apply uncertainty buffers, and get a realistic range estimate instead of a single wrong number.
UTM Link Builder
Build campaign URLs with utm_source, medium, and campaign — presets, validation warnings, and a parameter reference.

Dev Utilities & Fun

README Generator
Build a practical project README with installation, usage, commands, environment variables, and badges.
Dockerfile Generator
Generate Dockerfiles for Node.js, Next.js, Astro, Bun, and static sites — with .dockerignore and build commands.
Markdown Table Generator
Build markdown tables in an editable grid — paste from Excel or Sheets, set alignment, copy pretty-printed output.
Markdown Preview
Live markdown to HTML preview with GFM quirks explained — raw HTML in the input is safely escaped.
Diff Checker
Compare two text blocks line by line — unified or side-by-side view, ignore-whitespace option, change stats.
Text Cleaner & Whitespace Remover
Collapse spaces, clean blank lines, normalize line endings, expand tabs, or turn pasted text into one line.
Reverse Text & Unicode Explorer
Reverse visible characters, words, lines, or entire text without breaking emoji and combining marks.
Fake Data Generator
Generate reproducible fake JSON across 25 dataset types — people, commerce, content, work, events, files, API logs, sensors, and more.
YAML ↔ JSON Converter
Convert YAML to JSON and back with indent options, line-number errors, and warnings for classic YAML gotchas.
JSON ↔ CSV Converter
JSON arrays to CSV and back — nested-object flattening, delimiter auto-detect, type inference, proper RFC 4180 quoting.
JSONL ↔ JSON Converter
Convert JSONL (JSON Lines, NDJSON) to a JSON array and back, with per-line validation, error positions, and key counts.
Base64 Image Encoder / Decoder
Turn images into data URIs (or decode base64 back to a preview) with HTML and CSS snippets — files never leave your browser.
Code Beautifier & Minifier
Format or minify HTML, CSS, and JavaScript in your browser — with before/after byte counts.
HTML to JSX Converter
Paste HTML, get JSX — className, style objects, self-closed tags, SVG attributes, and comments handled.
Line Sorter & Deduplicator
Sort, dedupe, filter, trim, and transform lines of text — operations compose, with live in/out stats.
Lorem Ipsum Generator
Classic lorem ipsum plus dev ipsum and fake commit messages — seeded and reproducible, as text, HTML, or markdown.
Password Generator
Passwords, passphrases, PINs, and random bytes via crypto.getRandomValues — with entropy bits and time-to-crack estimates.
QR Code Generator
QR codes for URLs, text, or WiFi networks — SVG and PNG export, generated entirely in your browser.
Markdown TOC Generator
Paste markdown, get an anchor-linked table of contents — GitHub-style slugs, duplicate handling, indent options.
Image Resizer & Compressor
Resize and compress images right in the browser with before/after sizes — files never get uploaded anywhere.
EXIF Viewer & Stripper
See what metadata your photos leak — camera, settings, GPS location — and strip it all client-side before sharing.
Stack Personality Quiz
What does your stack say about you? Eight questions, one archetype: Hetzner Monk, Serverless Maximalist, or worse.
Markdown ↔ HTML Converter
Convert markdown to HTML source and HTML back to markdown — GFM tables, nested lists, code blocks, all in the browser.
XML Formatter & Validator
Pretty-print or minify XML and check it is well-formed — CDATA, comments, and declarations preserved exactly.
XML to JSON Converter
Convert XML to JSON and JSON back to XML in your browser. Attributes, repeated elements, and text follow one documented mapping.
Phone Number Formatter
Validate any phone number and format it as E.164, international, national, or a tel: URI — powered by libphonenumber.
Unicode Character Search
Find any character by name or paste one to decode it — code points, UTF-8 bytes, and HTML, JS, CSS escapes with copy buttons.
Open Source License Chooser
MIT, Apache, GPL, or MPL? A short quiz plus a permissions comparison table — with full license texts ready to download.
TOML to JSON Converter
Convert TOML to JSON and JSON back to TOML in the browser. Dates become strings, NaN and Infinity become null, and a null value is rejected on the way back.