OpenAPI Formatter Online — Beautify JSON & YAML Specs
Pretty-print OpenAPI 3.0–3.2 documents (JSON or YAML) in your browser — 2 or 4 space indent, nothing uploaded.
Developer notes
• Generic pretty-print (JSON.stringify / yaml.dump) — not an OpenAPI-aware key reorderer. • Input kind is preserved: JSON in → JSON out; YAML in → YAML out. • YAML comments are lost on format. • Numeric openapi versions in YAML (e.g. 3.0) are normalized to strings (3.0.0). • Max input 512 KiB.
Use cases
• Clean up minified or hand-edited OpenAPI JSON/YAML before review. • Normalize indentation (2 or 4 spaces) for PR diffs. • Pair with Validate OpenAPI after formatting.
Examples
Compact JSON → indented
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YAML preserved as YAML
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Format OpenAPI FAQ
Common questions
Does format preserve JSON vs YAML?
Yes. JSON input produces indented JSON; YAML input produces YAML via yaml.dump. Comments in YAML are not preserved.
Is this an OpenAPI-aware pretty printer?
No — it is a generic pretty-print (JSON.stringify / yaml.dump). Keys are not reordered to OpenAPI conventions.
What about openapi: 3.0 as a YAML number?
Numeric versions are normalized to strings (3 → 3.0.0, 3.0 → 3.0.0) before output.
Which OpenAPI versions?
OpenAPI 3.0, 3.1, and 3.2. Swagger 2.0 is not supported — use our OpenAPI tools only for 3.x.
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