Reliable transforms
Format, validate, convert, and compare data without generated scripts or hand-edited payloads.
Deterministic compute for agents
Stop spending tokens on JSON plumbing.
One HTTP API that formats, validates and converts JSON, CSV, YAML and XML, compares two documents, and handles Base64, URL, HTML entity and JWT decoding. Start with familiar developer tools, then automate the same contracts when you need to.
28 endpoints Versioned contract Agent-ready
Token budgetEstimated
40–80%fewer transformation tokens in typical tool-assisted workflows
Illustrative estimate. Savings vary with payload size and integration; keeping large payloads outside the model context can save more than sending them as tool arguments.
JSONCSVYAMLXMLFormatValidateConvertDiff
One request
Convert JSON to CSV
in a single call.
Every operation uses the same envelope: a versioned URL, a JSON body, an explicit result, and a stable error shape. No prompt engineering and no parsing prose back into data.
REQUESTPOST /v1/json/to-csv
curl -X POST https://api.jsonkit.tools/v1/json/to-csv \ -H "Content-Type: application/json" \ -d '{ "input": "[{\"id\":1,\"agent\":\"Atlas\"}]", "responseMode": "plain" }'
RESPONSE · 200text/plain
id,agent 1,Atlas
Built for automation
Deterministic tools,
not generated code.
Language models are excellent planners and expensive serializers. Deterministic utilities keep routine transformations fast, repeatable, and easy to inspect.
One response shape
Every endpoint returns ok plus either result or a structured error with a machine-readable code.
JSON or plain text
Use a typed JSON envelope in applications or request the clean transformed document with no wrapper.
Ephemeral processing
Requests are transformed in memory. The API design does not require storing user payloads.
Close to every agent
The API is designed for Cloudflare's global network, with small handlers and no round trip to a database.
Stable from day one
The version lives in every URL. Breaking changes belong in a new namespace, never a silent response change.
The full surface
28 operations for JSON,
CSV, YAML and XML.
Pretty-print or minify a document, catch the line that breaks it, check it against a JSON Schema, move it between formats, or compare two versions by structure instead of by whitespace. Encoding, hashing and identifier helpers cover the rest of the everyday work. Each name below opens its request and response contract in the reference.
JSON
Convert
Compare
Encode & decode
Developer utilities
Agent workflows
Before your first call
Questions people
ask first.
Short answers to what usually decides whether an API is worth wiring up. The reference has the rest, and /openapi.json has the machine-readable version of all of it.
What can the JSONKit API do?
Twenty-eight operations over HTTP: format, minify and validate JSON, validate it against a JSON Schema, convert between JSON, CSV, YAML and XML, generate TypeScript interfaces from a payload, diff two JSON, YAML or XML documents, encode and decode Base64, URL escapes and HTML entities, decode a JWT, hash text, generate UUIDs, parse timestamps and convert colors.
Do I need an API key?
No. There is no signup and no key. CORS allows every origin, so a browser, a script or an agent can call it directly. A rate limit applies per IP address to keep the service available.
How do I convert JSON to CSV in one request?
POST your document to /v1/json/to-csv with { "input": "…" }. Add "responseMode": "plain" and the response body is the CSV itself, with no JSON wrapper to unpack. The same pattern works for YAML, XML and TypeScript output.
Is my data stored?
No. Every request is parsed, transformed and answered in memory. Nothing is written to disk or to a database, and there is no account to attach a payload to.
How is this different from the free tools on jsonkit.tools?
Same tested core, different delivery. The website runs it in your browser for a document you have in front of you; the API runs it over HTTP for code, CI pipelines and agents that need the same answer without a person in the loop.
Is there an OpenAPI specification?
Yes. /openapi.json is an OpenAPI 3.0 document generated from the same catalog that renders the reference, so every endpoint, option, default and error code in it is the one the service actually enforces.
What are the size limits?
A request body may be up to 1 MiB, a response up to 4 MiB, and parsed JSON may nest up to 100 levels. Exceeding a limit returns a structured error, never a truncated document.
JSON is only the start
28 focused operations.
One small contract.
/json/format/json/validate/json/diff/json/to-csv/csv/to-json/yaml/to-json/xml/to-json/json/to-typescript