Data · Best format for…

Best Data Format for APIs

APIs optimize for machines; configs optimize for humans. Converting at the boundary keeps both sides happy.

Quick take: JSON is the default API payload. XML when standards require it. YAML/TOML for human-edited config — convert to JSON for strict APIs.

JSON XML YAML TOML CSV JSON → CSV CSV → JSON YAML → JSON XML → JSON

Formats to consider

JSON

Best default API format

Native to JavaScript and every backend ecosystem.

Pros

Ubiquitous
Compact vs XML

Cons

No comments in strict JSON

What is JSON?JSON hub

XML

Best when a schema/standard demands it

Enterprise and document standards.

Pros

XSD/namespaces

Cons

Verbose

What is XML?XML hub

YAML

Best human config

K8s, CI, Compose.

Pros

Readable
Comments

Cons

Indent bugs

What is YAML?YAML hub

TOML

Best typed minimal config

Cargo and modern CLIs.

Pros

Clear types

Cons

Less universal than JSON on the wire

What is TOML?TOML hub

CSV

Best flat tabular exports

Not nested APIs.

Pros

Sheets

Cons

No nesting

What is CSV?CSV hub

Recommendations by situation

New public REST API

Pick: JSON

Client expectations.

Legacy industry XML API

Pick: XML

Do not fight the standard.

Kubernetes manifest

Pick: YAML (JSON when an API requires it)

Humans edit YAML.

Convert now

Turn the recommendation into a file — every converter between these formats is linked below. Processing stays in your browser.

JSON → CSV CSV → JSON YAML → JSON XML → JSON TOML → JSON CSV → XML CSV → YAML JSON → TOML JSON → XML JSON → YAML TOML → YAML XML → CSV XML → YAML YAML → CSV YAML → TOML YAML → XML

All related converters (58)

Related comparisons

JSON vs XML CSV vs JSON

Related “best format” guides

Best Spreadsheet Format for Data Exchange

FAQ

Should APIs accept YAML?

Usually accept JSON on the wire; let humans author YAML and convert.

Browse all best format guides or jump to every converter.