Free Tools

Developer tools for APIs & JSON

Free, browser-based tools for the formats and standards every API speaks. No signup, no rate limits, no upload — everything runs client-side. Built by the team behind Specway.

JSON & data

Format, validate, and convert the data formats every API speaks.

JSON Formatter

Pretty-print or minify JSON. Native browser parse.

JSON Validator

Pinpoint JSON syntax errors with line/column refs and stats.

YAML ↔ JSON Converter

Bidirectional YAML/JSON conversion — js-yaml powered.

JSON Schema Validator

Validate JSON data against a JSON Schema contract.

API & OpenAPI

Build, validate, and migrate OpenAPI specs without leaving the browser.

OpenAPI Validator

Validate OpenAPI 3.x specs with @apidevtools/swagger-parser.

OpenAPI Viewer

Paste a spec, get an interactive endpoint browser.

OpenAPI Linter

Check OpenAPI specs against documentation-quality rules.

OpenAPI Diff

Diff two OpenAPI specs to surface breaking changes.

Swagger 2 → OpenAPI 3

Migrate Swagger 2.0 specs to OpenAPI 3.x.

OpenAPI → TypeScript

Generate TS interfaces from OpenAPI schemas.

OpenAPI → Postman

Convert OpenAPI to a Postman v2.1 collection.

HAR → OpenAPI

Build an OpenAPI spec from a browser HAR capture.

Auth & code

Inspect tokens and convert curl commands to real code.

JWT Decoder

Decode JWT header and payload. Detects expiry. No upload.

cURL → Code

Convert curl to JS fetch / Python requests / Node / Go.

Regex Tester

Live match highlighting with capture groups.