56 Free Developer Tools. One Page. Zero Dependencies.
Published: (March 4, 2026 at 08:13 PM EST)
4 min read
Source: Dev.to
Source: Dev.to
I built 56 browser‑based developer tools. Every single one is a standalone HTML file — no npm, no build step, no signup, no tracking.
Key principles
- Single HTML file — view source, it’s all there
- Runs in your browser — nothing leaves your machine
- No dependencies — works offline after the first load
- Dark theme — because it’s 2026
General Tools
| Tool | What it does |
|---|---|
| JSON Format | Beautify, validate, minify, tree view |
| Regex Test | Live matching, capture groups, 12 presets |
| Diff Text | Side‑by‑side line + word diff |
| Cron Explain | Plain English description + next 10 run times |
| Base64 | Encode/decode text and files |
| Hash Gen | MD5, SHA‑1, SHA‑256, SHA‑512 |
| JWT Builder | Create & decode JWTs |
| URL Parser | Break URLs into components |
| UUID Gen | v4 UUIDs, bulk generate |
| Timestamp | Unix ↔ human time, timezone conversion |
| HTML Escape | Encode/decode HTML entities |
| Lorem Gen | Lorem ipsum paragraphs, sentences, words |
| Password Gen | Configurable secure passwords |
| CSV ↔ JSON | Bidirectional conversion with table preview |
| YAML ↔ JSON | Includes a Docker Compose sample |
| TOML ↔ JSON | Presets for Cargo.toml, pyproject.toml |
| SQL Format | Beautify + minify SQL queries |
| Markdown Table | Visual editor → formatted markdown |
CSS & Design Tools
| Tool | What it does |
|---|---|
| Color Palette | 6 harmony schemes, WCAG contrast checker |
| Color Convert | HEX ↔ RGB ↔ HSL ↔ HSB ↔ CMYK |
| Font Pair | 20 Google Font pairings |
| CSS Shadow | Box‑shadow generator |
| CSS Gradient | Linear/radial gradient builder |
| CSS Flex | Flexbox playground |
| CSS Grid | Grid layout generator |
| CSS Animation | Keyframe animator, 12 presets |
| CSS Filter | Blur, contrast, sepia, etc. |
| Border Radius | 8‑point control, 10 presets |
| Box Model | Interactive margin/padding visualizer |
| Spacing Calc | Design‑system scale generator |
| CSS Units | px ↔ rem ↔ em ↔ vw ↔ vh |
| Aspect Ratio | Calculate and convert ratios |
| SVG Preview | Paste SVG, see it live |
| Favicon Gen | Generate favicons from text/emoji |
| Text Transform | camelCase, snake_case, UPPER, etc. |
| Image Resize | Resize in browser, keep aspect ratio |
| Emoji Picker | Search and copy emoji |
Network & System Tools
| Tool | What it does |
|---|---|
| chmod Calc | Permission calculator |
| HTTP Status | All status codes explained |
| DNS Lookup | A, AAAA, MX, NS, TXT records |
| SSL Check | Certificate expiry checker |
| Headers Check | HTTP response headers viewer |
| IP Info | Your IP, geolocation, ISP |
| Meta Tags | OG/Twitter meta tag generator |
| QR Code | Generate QR codes |
Content & Analytics Tools
| Tool | What it does |
|---|---|
| Word Count | Words, characters, reading time |
| Title Score | Blog title analyzer |
| README Score | README quality checker |
| GitHub Stats | Repo analytics dashboard |
| npm Health | Package health score |
| LLM Price | Compare AI model pricing |
| Prompt Price | Calculate prompt costs |
| Model Picker | Choose the right AI model |
| AI ROI Calc | AI investment calculator |
| Dev.to Stats | Article analytics |
| Markdown Preview | Live markdown renderer |
Every tool is hosted on GitHub under the user yurukusa. Feel free to fork, self‑host, or modify them — they’re just HTML files.
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