Free JSON tools that run entirely in your browser
JSON is the lingua franca of the modern web — every REST API, every configuration file, every NoSQL document store speaks it. But working with JSON day-to-day still means running into the same small headaches: a missing comma that breaks the parser, a response from a new endpoint that needs to be turned into TypeScript interfaces, a CSV file that a stakeholder wants in JSON form. Lintify is a focused toolkit that solves these problems quickly, without getting in your way.
Every tool on this site runs entirely in your browser. There is no backend that receives your data, no database that stores it, no analytics pipeline that profiles it. When you paste a JSON document into the validator, the parsing happens in the JavaScript engine you are already running. When you convert JSON to CSV, the conversion is done with the same JavaScript library you would use yourself. This is not just a privacy feature — it also makes the tools instant. There is no network round-trip, so even a multi-megabyte file formats in the time it takes to redraw the screen.
What you can do with Lintify
The toolkit is organised into four broad categories. The validators and formatters cover the everyday work of checking syntax, beautifying minified payloads, comparing two documents, and visualising deeply nested structures. The schema and query tools help you enforce contracts with JSON Schema, find data inside a document with JSONPath, and inspect JSON Web Tokens before trusting them. The converters move data between JSON and the formats your tools expect — CSV for spreadsheets, YAML for config files, XML for legacy systems, SQL for databases, and Excel for stakeholders who refuse to leave it. Finally, the code generators turn sample JSON into typed classes for TypeScript, Java, Python, C#, and Go, so you can stop hand-writing boilerplate and get back to the actual work.
Why browser-side JSON tools matter
Many online JSON tools send your data to a server, run the conversion there, and send the result back. That is fine for a public dataset, but it is the wrong default for the kind of data developers usually work with — API responses that contain real user records, configuration files with secrets, log payloads from production. Lintify makes privacy the default rather than an opt-in. If your data never leaves your machine, it cannot be logged, leaked, or sold.
There is also a practical benefit: browser-side tools are faster. The bottleneck for a JSON operation is almost never CPU — it is the network round-trip. By skipping the round-trip entirely, Lintify can validate a 5 MB JSON file in the time a server-based tool would still be waiting for the upload to finish.
How Lintify is built
Lintify is a static site built with Next.js and deployed to Cloudflare Pages. The tools themselves are thin React wrappers around the same open-source JavaScript libraries you would reach for in your own code — ajv for JSON Schema validation, js-yaml for YAML, json2csvfor CSV conversion, jsonpath-plus for JSONPath queries, and so on. There is no proprietary engine under the hood. If a tool ever stops working, you can reproduce its behaviour in a Node REPL with the same libraries.
The site is free to use, free to link to, and free to share. There is no signup, no rate limit, and no daily quota. If you find a bug or want a new tool, the source is on GitHub — pull requests are welcome.