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Listed in Coding & Development with 261 other toolsPart of 1443+ curated AI tools on AISO
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webtoolz

A free, open-source, entirely browser-side toolkit of developer utilities — JSON tooling with AI auto-repair, an MCP config generator for 40+ servers, a token counter with cost estimates and a Mermaid editor.

freeFree and open source, described on the site as 'Free forever'. Everything runs in the browser with no signup and no uploads, and there is no paid tier or usage cap published anywhere on the site.View full pricing →

Visit webtoolz

https://webtoolz.dev

About webtoolz

webtoolz is a free, open-source collection of developer and creator utilities that all run client-side in the browser — no signups, no uploads, nothing sent to a server. The JSON section is the deepest part of it: format and beautify, validate, diff and compare, convert between formats, build mock APIs, generate share links, and an AI auto-repair mode that takes malformed JSON and fixes it rather than just reporting the parse error. A Mermaid Studio gives a live-preview diagram editor with four themes and unlimited PNG and SVG export, again entirely client-side. The AI section is aimed at people building with large language models and includes a token counter with cost estimates, plus an MCP config generator covering more than forty MCP servers and six AI clients — useful if you have ever hand-written a client config and got the transport or the argument array subtly wrong. There is also an AI Music Studio that generates original songs with AI-written lyrics across sixteen-plus genres with synced lyrics, and a set of media tools. The whole thing is positioned as a toolkit you bookmark rather than an account you create, which for anything involving pasting production JSON or API keys is the meaningful design decision.

Key Features

Complete JSON toolkit — format, validate, diff, convert, mock API builder, share links
AI auto-repair for malformed JSON
MCP config generator covering 40+ MCP servers and 6 AI clients
Token counter with cost estimates
Mermaid Studio with live preview, 4 themes and unlimited PNG/SVG export
100% client-side — no signups, no uploads

Tags

jsonmcpopen-sourcedeveloper-toolsbrowser-based
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