String Utility Belt MCP Server

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

Other surfaces

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

MIT