Mcp

com.stringutilitybeltv1.3.3Updated Oct 6, 2026

MCP server exposing String Utility Belt's utilities and pipelines as tools for AI agents.

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Overview

AI-generated overview

Exposes String Utility Belt's 246 text, encoding, hash, cipher and data-format utilities and pipelines as local tools for an AI assistant.

What it does: Runs the String Utility Belt engine locally over stdio and offers its utilities and pipelines as agent tools. The underlying engine covers encodings, hashes, ciphers, compression, data formats such as JSON, YAML, TOML, CSV and XML, line and text operations, analysis, generators, numbers, dates and colours. Pipelines can chain transformations with per-step previews, conditional steps, parallel branches and macros.
When to use it: Useful when an assistant needs to transform or inspect strings and structured data locally: encoding or decoding base64, computing hashes, converting between JSON, YAML, TOML, CSV and XML, or running repeatable multi-step text pipelines. It is a general-purpose text and data utility set rather than a service integration.
Requirements: Runs as a local process on the user's machine via the npm package @string-utility-belt/mcp over stdio. Node.js is required (the project states Node.js 20.19+ or 22.12+). No authentication, environment variables or headers are declared. Desktop only; not available as a web executable.

Before you install

No credentials, secrets, payments or write actions are declared in the manifest. The README notes that custom JavaScript steps run in a sandboxed, network-less iframe and worker, and that steps arriving from someone else's share link are quarantined, which suggests untrusted pipeline content should be treated with care.

Installation

In SourceWeft

Open Mcp in the dashboard and add it to a workspace.
Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

String Utility Belt

[CI] [License: MIT] [npm: subelt] [smithery badge]

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:

Development

Requires Node.js 20.19+ or 22.12+.

bash

git clone https://github.com/Murraylr/string-utility-belt.gitcd string-utility-beltnpm cinpm run dev          # generates the utility manifest, then starts Vitenpm test             # Vitest (unit, component, golden-example and property tests)npm run lintnpm run typecheck

git clone https://github.com/Murraylr/string-utility-belt.gitcd string-utility-beltnpm cinpm run dev          # generates the utility manifest, then starts Vitenpm test             # Vitest (unit, component, golden-example and property tests)npm run lintnpm 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

MIT

Source: README.md at commit e926e4a

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Version history

v1.3.3LatestOct 6, 2026

Mcp