com.stringutilitybelt/mcp
MCP server exposing String Utility Belt's utilities and pipelines as tools for AI agents.
String Utility Belt
stringutilitybelt.com · Usage guide · All utilities · Integrations
Chain string transformations into visual pipelines with live, per-step previews. 246 utilities — encodings, hashes, ciphers, compression, data formats (JSON/YAML/TOML/CSV/XML), line and text operations, analysis, generators, web/dev helpers, numbers, dates and colours — all running client-side, with the same engine available as a CLI, an HTTP API, an MCP server, a browser extension and a VS Code extension.
Features
- Pipelines — add, reorder (drag and drop), duplicate, disable/solo steps; undo/redo; per-step previews, diffs, timings and error policies (pass through / stop / empty); conditional steps; parallel branches with concat/zip/json/pick merges; macros (collapse a sub-chain into one step).
- Share and save — pipelines (and optionally the input) as compressed
#/p/…links, a named pipeline library with JSON import/export, a preset gallery, an embeddable#/embed/…widget. - Magic — detects the input's format (base64, JWT, gzip, JSON, …) and suggests or appends the decoding step; "decode until stable" mode.
- Input/output — file upload (text and binary), fetch-a-URL via the Worker proxy, input history, side-by-side and diff views, hex view for bytes, syntax highlighting, stats bar, smart download names, copy-as (raw / JSON literal / hex / base64).
- Engine — runs in a Web Worker with cancellation, adaptive debounce, a chunked mode for multi-MB inputs and a preview-first-64 KB option; custom JavaScript steps run in a sandboxed, network-less iframe + worker, and are quarantined when they arrive from someone else's link.
- App — command palette (Ctrl+K), keyboard shortcuts (
?), fuzzy utility search with favourites/recents and type-aware badges, light/dark themes, per-utility doc pages with a live playground, installable PWA with offline support and an OS share target, i18n scaffold.
Using the app
Open stringutilitybelt.com — nothing to install, and every
transformation runs in your browser (see the privacy policy
for the few features that contact the server). The how-to guide lives in the app
itself: click Docs in the header, or go to /docs/. Each
utility's settings and examples are on its own page, listed at
/utilities/.
From a terminal, the same engine is one command away:
echo -n hello | npx subelt trim base64_encode hash # SHA-256 of the base64
Development
Requires Node.js 20.19+ or 22.12+.
git clone https://github.com/Murraylr/string-utility-belt.git
cd string-utility-belt
npm ci
npm run dev # generates the utility manifest, then starts Vite
npm test # Vitest (unit, component, golden-example and property tests)
npm run lint
npm run typecheck
| Command | What it does |
|---|---|
npm run gen | Regenerate src/utilities/_generated/* (run automatically before dev/build) |
npm run build | Production build of the web app |
npm run check:bundle | Enforce the entry-chunk budget in bundle-budget.json |
npm run build:seo | Pre-render utility pages, sitemap, RSS and OG images into dist/ (build:seo:fast skips OG images) |
npm run build:site | build + build:seo |
npm run build:tools | Build packages/* (core, CLI, MCP server, browser extension, VS Code extension) |
npm run test:e2e | Playwright end-to-end tests against a production build |
npm run bench | Large-input benchmarks (vitest bench) |
npm run deploy | build:site, then wrangler deploy (Cloudflare Workers: static assets + /api/*) |
Other surfaces
| Surface | Where | Notes |
|---|---|---|
| Core library | packages/core | Framework-free engine + all utilities |
| CLI | packages/cli | echo -n hello | subelt base64_encode |
| MCP server | packages/mcp | Utilities and pipelines as agent tools over stdio |
| HTTP API | worker/ | POST /api/run, GET /api/utilities[/:id] (CORS, rate-limited) |
| Browser extension | packages/extension | MV3; context menu "run on selection" |
| VS Code extension | packages/vscode | Transform selection, run a share link |
Contributing
Contributions are welcome — bug reports, utility ideas and pull requests. Start with CONTRIBUTING.md (setup, adding a utility, PR checklist) and the Code of Conduct. CLAUDE.md is the detailed architecture reference.
Found a security issue? Please report it privately — see SECURITY.md.
License
Installation
Source-derived launch command. Check the maintainer’s required arguments and credentials before running:
npx -y @string-utility-belt/mcpSet up in your AI client
Merge this template into ~/Library/Application Support/Claude/claude_desktop_config.json. Keep existing servers. Add any arguments, credentials, and permissions required by the maintainer; this template has not been install-tested.
{
"mcpServers": {
"com-stringutilitybelt-mcp": {
"command": "npx",
"args": [
"-y",
"@string-utility-belt/mcp"
]
}
}
}Restart Claude Desktop completely for changes to take effect. Confirm the server appears connected in the client’s tool list, then try a read-only example from its documentation.
Claude Desktop setup referencePackage
@string-utility-belt/mcpnpmCompatible MCP Clients
com.stringutilitybelt/mcp works with any MCP-compatible client. Copy the config snippet from the Configuration section above and add it to the file shown for your client, then restart the application.
- Claude Desktop
~/Library/Application Support/Claude/claude_desktop_config.jsonRestart Claude Desktop completely for changes to take effect. - Cursor
~/.cursor/mcp.jsonRestart Cursor for changes to take effect. - VS Code
.vscode/mcp.jsonReload VS Code window for changes to take effect. - Windsurf
~/.codeium/windsurf/mcp_config.jsonRestart Windsurf for changes to take effect. - Claude Code
.mcp.jsonSave at the project root, then start Claude Code in that project and review the MCP server approval prompt. Keep real credentials out of shared files.