Coding.Tools

The Developer Toolbox

63 free, browser-based developer tools that respect your privacy.

No sign-up. No tracking. Website tools run in your browser. A small optional A2A runtime exposes a server-side subset of deterministic tools for agent-to-agent calls.

English | 中文

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Why Coding.Tools?

• Privacy first: tools run locally in the browser.
• Static-first design: the production website is plain HTML, CSS, JavaScript, and static assets.
• A2A runtime: /a2a/* exposes supported deterministic tools for agent clients.
• Multilingual: English plus 8 localized language trees.
• No framework runtime: Eleventy generates the site; tools use vanilla JavaScript.
• Checked translations: npm run check validates page coverage, translation shape, category counts, and common localized-template regressions.

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Tools at a Glance

Category	Tools	What You Can Do
Hash & Cryptography	8	Base64, MD5, SHA-1/256/384/512, password generation
Number Conversion	26	Hex, decimal, binary, octal, ASCII, Roman numerals, RGB/RGBA, fractions, percentages
String & Text Utilities	8	Text editing, regex testing/replacement, word and character counts, case conversion
Formatter & Minifier	14	JSON, XML, HTML, CSS, JavaScript, SQL formatting and minification, JSON/XML conversion
Image Utilities	7	PNG/JPEG compression, progressive JPEG, Photo2Pixel, image Base64, EXIF viewing/removal

63 tools across 5 categories, available in 9 languages.

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Quick Start

npm install
npm run dev

The Eleventy dev server runs at http://localhost:5500.

Commands

npm run check          # Validate structure, i18n coverage, categories, and localized templates
npm run build          # Run check, then build the static site into dist/
npm run dev            # Eleventy dev server on localhost:5500
npm run debug          # Eleventy dev server with debug logging
npm run a2a            # A2A runtime on localhost:5510
npm run a2a:test       # Validate the A2A runtime endpoints
npm run mcp            # MCP stdio server for local MCP clients
npm run mcp:test       # Validate MCP HTTP and stdio interfaces
npm run skills:generate # Generate English Codex skills for every MCP tool
npm run skills:check   # Validate generated Codex skills and installer metadata
npm run docker:build   # Build the nginx-based Docker image
npm run docker:run     # Run the Docker image on localhost:8080
npm run docker:smoke   # Verify the running Docker container
npm run docker:stop    # Stop and remove the local Docker test container
npm run docker:test    # Build, run, and verify the Docker image

The website is served from the generated dist/ directory. The A2A/MCP runtime is a separate Node process proxied by nginx under /a2a/* and /mcp. Set SITE_BASE_URL when building for a non-production host, for example docker build --build-arg SITE_BASE_URL=http://localhost:8080 -t coding-tools ..

MCP

The MCP runtime exposes every entry in src/_data/tools.json through tools/list. Deterministic server-side tools execute directly through tools/call; browser-only image tools return a typed MCP tool error with a link to the web UI.

For HTTP clients, send JSON-RPC requests to /mcp with Content-Type: application/json, Accept: application/json, text/event-stream, and MCP-Protocol-Version: 2025-06-18. For MCP clients that hide JSON-RPC details, configure the endpoint and pass only the params.arguments object shown in each skill's Example Arguments section.

HTTP endpoint:

curl http://localhost:5510/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -H 'MCP-Protocol-Version: 2025-06-18' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"sha256-generator","arguments":{"input":"abc"}}}'

Local stdio server command for MCP clients:

node server/mcp-stdio.js

Codex Skills

This repository includes English Codex skills for every Coding.Tools MCP tool. Each skill contains the MCP tool name, input schema, output schema, example arguments, parsing guidance, and a production endpoint.

The bundled examples use synthetic, non-sensitive values. Tools that need no input, or browser-only image tools that only return a web UI link through MCP, intentionally use {} as their example arguments.

Install all bundled skills from a GitHub checkout with:

npx github:<owner>/<repo>

For a fork or a private checkout, replace <owner>/<repo> with the GitHub repository path. The installer copies skills to $CODEX_HOME/skills when CODEX_HOME is set, otherwise to ~/.codex/skills.

Useful installer options:

npx github:<owner>/<repo> -- --list
npx github:<owner>/<repo> -- --dry-run
npx github:<owner>/<repo> -- --force
npx github:<owner>/<repo> -- --target ./my-skills

Regenerate and validate the skill bundle after MCP schema changes:

npm run skills:generate
npm run skills:check

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Architecture

coding-tools/
├── .eleventy.js                 # Eleventy configuration
├── Dockerfile                   # Static nginx container for dist/
├── package.json                 # npm scripts and dependencies
├── scripts/
│   └── check-structure.js       # Structure and i18n validation
├── src/
│   ├── index.njk                # English homepage
│   ├── localized-index.njk      # Localized homepage generator
│   ├── sitemap.xml.njk          # Sitemap for all languages and tools
│   ├── robots.txt.njk
│   ├── _includes/               # Layouts, partials, and macros
│   ├── _data/
│   │   ├── site.js              # Site metadata and language list
│   │   ├── tools.json           # Tool metadata
│   │   ├── categoryDefinitions.json
│   │   ├── categories.js
│   │   ├── homepage.json        # Homepage translations
│   │   ├── t/                   # Per-language UI translations
│   │   ├── t.js                 # Loads t/*.json
│   │   ├── toolData/            # Per-tool translated content
│   │   └── toolData.js          # Loads toolData/*.json
│   ├── css/
│   │   ├── style.css
│   │   └── tool.css
│   ├── js/                      # Shared client-side utilities and bundled libraries
│   ├── assets/                  # Favicons, images, and Photo2Pixel ONNX model
│   └── tools/
│       ├── *.njk                # English tool pages
│       ├── cn/ tw/ jp/ kr/      # CJK localized tool pages
│       └── fr/ de/ es/ pt/      # European localized tool pages
└── dist/                        # Generated output, gitignored

Tech stack: Eleventy v3, Nunjucks, custom CSS, vanilla JavaScript.

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Internationalization

Supported languages:

Language	Code	HTML lang
English	en	en
Chinese Simplified	cn	zh-CN
Chinese Traditional	tw	zh-TW
Japanese	jp	ja
Korean	kr	ko
French	fr	fr
German	de	de
Spanish	es	es
Portuguese	pt	pt

Localized tool pages set lang and toolId in frontmatter, then render translated content through {{ t.ui.* }} and {{ toolData.* }}. Metadata such as title, description, tool title, and category name is computed from toolData by src/_data/makeToolLangData.js.

Do not add localized frontmatter fields like title, description, toolTitle, toolDescription, or categoryName; they override translated data and are rejected by npm run check.

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Validation

npm run check verifies:

• every language listed in site.js exists in homepage and UI translation data
• every tool in tools.json has one src/_data/toolData/<slug>.json
• every toolData file has all 9 languages with matching keys and array lengths
• localized non-empty English baseline fields are not empty
• category counts match actual tools
• every English and localized tool template exists
• localized templates have correct lang, toolId, and permalink data
• localized templates do not use metadata frontmatter overrides or known hard-coded English UI strings

npm run build runs this validation first through prebuild.

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Adding or Updating a Tool

1. Add or update metadata in src/_data/tools.json.
2. Add or update translated content in src/_data/toolData/<slug>.json.
3. Add any shared UI strings to src/_data/t/<lang>.json for every language.
4. Create or update the English template in src/tools/<slug>.njk.
5. Create or update localized templates in each language directory.
6. Run npm run check and npm run build.

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License

MIT License.

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