Methodology

Where the tools run

Every JsonKit tool runs in your browser. The page loads the tool's code once, and from then on your input is processed on your own device. Nothing you paste or upload is sent to a server, so the output you see is exactly what the tool's engine produced from your input.

How results are computed

Formatting, minifying and validating JSON uses the browser's built-in JSON parser and serializer, the same engine that runs JSON.parse and JSON.stringify in JavaScript. Other formats use established open-source parsers that run in the browser: yaml for YAML, smol-toml for TOML, fast-xml-parser for XML, Papa Parse for CSV and SheetJS for Excel files. The query testers run jsonpath-plus, the JMESPath community implementation and jq compiled to WebAssembly. MIME type lookups come from the mime-db dataset of IANA media types.

The token counter counts GPT tokens exactly with the gpt-tokenizer library. Other providers' tokenizers do not run in a browser, so counts for Claude, Gemini and Llama are estimates and are labeled as estimates on the page. Model prices are standard list prices, checked against each provider's pricing page on 2026-10-06. Prices change, so confirm them with the provider before relying on a cost figure.

What each tool is checked against

Each tool is mapped to the official or first-party references for the format it handles, such as RFC 8259 and ECMA-404 for JSON, the YAML 1.2.2 specification, the W3C XML 1.0 recommendation, RFC 4180 for CSV and RFC 7519 for JSON Web Tokens. The tool's behavior and the claims on its page are compared with those references. Every tool page lists its references under Sources & last verified, with the date of the last check.

Automated tests run the tool engines against sample inputs and known edge cases.

Review schedule

Each tool is reviewed again at least every 12 months, and sooner when its engine, a library it depends on or the referenced specification changes. Tool pages show the next review date beside the last verified date. Guides and glossary entries show the date they were last updated.

Corrections

Tool, guide and glossary pages have a Report an error link that opens an email to contact@toolur.com with the page address filled in. Reports are checked against the referenced specification. Confirmed fixes are released, the page's verified or updated date is changed, and notable changes are listed in the changelog.