Diff API FREE

Compare two text or JSON snippets. Unified, context, ndiff, side-by-side HTML, or structured JSON. Zero signup.

Try the interactive UI: /tools/diff

POST /diff/text

Compare two text snippets. Returns a diff in the requested format.

Body (JSON)

Field	Type	Default	Description
`a`	string	required	The "before" text (max 200,000 chars)
`b`	string	required	The "after" text (max 200,000 chars)
`a_label`	string	"a"	Label shown in diff header
`b_label`	string	"b"	Label shown in diff header
`context_lines`	int	3	Lines of context (0-20)
`ignore_whitespace`	bool	false	Collapse whitespace before compare
`ignore_case`	bool	false	Case-insensitive compare

Query: format

format	Returns	Notes
`unified` (default)	text/plain	Standard `git diff` style
`context`	text/plain	Old context diff style
`ndiff`	text/plain	Line-by-line markers (+/-/?)
`html`	text/html	Side-by-side HTML table (full page)
`json`	application/json	Summary + opcodes for programmatic use

Example

curl -X POST https://forge-node.tail2b516d.ts.net/diff/text?format=unified \
  -H 'Content-Type: application/json' \
  -d '{"a":"hello\nworld\n","b":"hello\nthere\n","a_label":"old.txt","b_label":"new.txt"}'

POST /diff/json

Compare two JSON values structurally. Both inputs are canonicalized (sorted keys, fixed indent) and a unified diff is returned, plus a summary.

Body

`a`	object/array	Required
`b`	object/array	Required
`sort_keys`	bool	Default true (recommended)
`indent`	int	0-8, default 2

Example

curl -X POST https://forge-node.tail2b516d.ts.net/diff/json \
  -H 'Content-Type: application/json' \
  -d '{"a":{"name":"forge","port":8080},"b":{"name":"forge","port":8081,"tls":true}}'

POST /diff/similarity

Returns just the summary block (added/removed lines, similarity ratio 0-1) without producing a full diff. Same body shape as /diff/text.

GET /health/diff

Service health check. Returns {"status":"ok"}.

Limits

Rate limited at 60 requests/minute per IP. Max input length 200,000 characters per side. No auth required.