About
Last updated 10 November 2026
A JSON workbench that never asks for the document.
What this is
Pikkola JSON is a formatter, a validator, a tree viewer and a type generator for JSON. Paste a response or drop a .json file: the left side keeps the text, the right side shows the same document as a tree, and the tabs beside it turn the document into TypeScript interfaces, a Zod schema, Python models or a JSON Schema. It is the eighth tool from Pikkola, a small studio in Seoul that writes single-purpose browser tools.
How it is built
Static files and no backend: one HTML page, one stylesheet, and a few hundred lines of plain JavaScript that the browser runs. There is no framework, no build step at runtime and no server side to call. Cloudflare Pages serves the files from an edge location near you. Pretendard, the Korean typeface, and JetBrains Mono, the code face, are both self-hosted, so opening the page contacts no font CDN.
The formatting is the browser's own strict JSON parser followed by a stringify with the indentation you picked. The tree is built from the parsed value, one row per key, with children laid out a page at a time. The converters walk the same value and infer a shape: objects become interfaces and models, arrays of objects are merged, keys missing from some elements become optional, and a null value makes its type nullable.
Why the document stays in the tab
An API response is often the most sensitive thing on a developer's screen: a bearer token, a customer record, a webhook body with an address in it. Most online JSON tools send it to their server to be formatted there. Nobody reads the terms, and the document is on someone else's disk before the page has finished loading.
This page makes no such request. The security policy it ships with blocks connections to other origins, the script has no fetch call in it, and there is no analytics tag that would carry the text away. You can confirm it in the Network tab of your browser's developer tools while you work. That is the whole privacy design: not a promise in a policy, a missing request.
What it costs
Nothing. No account, no trial, no watermark and no advertisement. Pikkola pays for its domains with three five-dollar field guides about asynchronous work. If a paid tier ever appears on this page it will be a different tool, with the price written on the page it lives on.
The rest of the shelf
- Pikkola Time: a time zone planner that scores the hours everyone can attend.
- Pikkola Diff: a text comparison that never uploads either side.
- Pikkola Rank: a pre-flight check for Korean blog drafts.
- Pikkola Meta: link cards and the meta tags behind them.
- Pikkola Invoice: a one-page invoice you print from the browser.
- Pikkola Journal: essays on distributed work and browser tooling.
- Pikkola Tools: a hand-checked directory for remote teams.
Contact
Write to hello@pikkola.com. A person reads it, usually within a few days. There is no support plan behind the address, but a bug report about a JSON document that broke the parser is genuinely welcome.