jsonversal
jsonversal — free in-browser toolkit

JSON & LLM developer tools that run in your browser.

No signup, no upload, no accounts. Every tool runs 100% on your device — paste JSON, infer schemas, count LLM tokens, and estimate API costs without your data ever leaving your browser.

Explore 69 tools Try JSON Schema Generator
100% local — nothing uploaded 0 sign-up — no accounts Free & unlimited — for devs
Core toolkit

JSON & LLM tools

Format, validate, transform and generate JSON — plus LLM token counting, schema generation and structured output helpers.

Showing 16 of 16 tools

LLM Token & Pricing Calculator

Estimate tokens and cost across GPT, Claude, Llama and Gemini.

Structured Output JSON Schema Generator

Create strict JSON Schema for LLM structured output.

JSON Schema Sample Data Generator

Generate sample JSON that satisfies your schema — mock data in seconds.

JSON to Pydantic Model

Generate Pydantic v2 BaseModel classes from a JSON sample.

JSON to Zod Schema

Infer a Zod validation schema from a JSON sample.

JSON to TypeScript Interface

Generate type-safe TypeScript interfaces from JSON.

JSONPath Tester

Test JSONPath expressions against your JSON and see every match.

JSON Diff

Compare two JSON documents and list every added, removed, changed value.

JSON Formatter & Validator

Pretty-print, validate, and minify JSON — with error line/column hints and document stats.

JSON to Go Struct

Generate Go structs with json tags from a JSON sample.

JSON to C# Class

Generate C# POCO classes with Newtonsoft attributes from JSON.

UUID v7 Generator & Timestamp Decoder

Generate RFC 9562 UUID v7 in bulk and decode the embedded timestamp.

Markdown Editor & Live Preview

Write Markdown and watch the HTML preview render as you type — safely.

Text Diff

Compare two texts with side-by-side and git-style unified diff output.

JSON Escape & Unescape

Escape plain text into a JSON string literal and decode escaped literals.

JSON Sorter & Deduper

Sort object keys and arrays, dedupe items, and pretty-print with stats.
Why local-first

Your data never leaves your browser — GDPR-friendly by design

Most online tools upload your input, process it on a server and hand something back. jsonversal does the opposite: every tool is a self-contained page that runs on your device. There is no upload step, no queue, and no server-side copy — and no third-party CDN watching you load it.

Nothing is uploaded

Tools run on the Web Crypto, File and Clipboard APIs inside your tab. Paste a JWT, a private key or a customer payload — it is never sent anywhere, so there is no server-side log to leak and nothing to delete.

No third-party CDNs

Fonts and libraries are served from this domain. Loading them from someone else's CDN would hand that provider your IP address on every page load — which is exactly the transfer European courts have ruled against.

No accounts, no profiling

No sign-up, no ad networks, no cross-site tracking. Analytics are cookieless and aggregate — we count page views, not people.

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