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Compare two API responses and see which fields changed

Upload the old and the new JSON response. You get every field that was added, removed or changed type, with its full path, for example a price that became a string.

or drop them here

JSON, JSONL · Up to 2 response samples
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Standard toolIncluded · 3 free jobs a dayFree: 3 jobs a dayPro: up to 200 jobs a day · €12.99/month or €89.99/year
  • JSON / JSONL
  • Up to 2 response samples
Prepared result preview · fictional sample dataFictional Two-Sample API Shape Comparator fixture
Source
2 prepared source files · 195 bytes
Reconciliation evidence
  • Samples: 2
  • Differences: 4

contract-diff.json · findings.csv · manifest.json

BringJSON, JSONL
GetShape-difference JSON, findings and source manifest
PrivacyEncrypted source · 24-hour result

One clear job, from source to download

  1. 1

    Add the source

    Supported formats and limits are visible before the upload.

  2. 2

    Confirm the settings

    Review the exact source, options, units and access before processing.

  3. 3

    Inspect and download

    Check the preview and warnings, then unlock the complete package.

Spotting field changes between two API responses

What you compare

You upload exactly two samples in JSON or JSONL. The old response is the baseline and the new one is the candidate. The tool walks both recursively and compares the field paths and their value types. A string whose text changes is not a finding. A field that changes type is, for example a price that used to be a number and now arrives as a string.

What the diff contains

You get contract-diff.json, findings.csv and manifest.json. contract-diff.json lists every field that was added, removed or changed type, with its full path. findings.csv holds the same differences as rows you can sort or share. For arrays, the shapes of all elements are merged, so a field that appears in only one element still shows up for that path. The manifest records a fingerprint of both source files.

What two samples cannot prove

There are no settings. The result reflects only the two files you supplied. A field missing from one sample may still be required in production, and a field present in both may still be optional. Read the diff as evidence of a change, not as a schema. Whether a change breaks your clients is a decision for you and for the team that owns the API.

Questions before you run it

What exactly does it compare?

One baseline sample and one candidate sample, walked recursively, reporting every field path that was added, removed or changed type between them.

Does it compare values or only types?

Paths and value types. A string whose text changes is not a finding; a string that becomes a number is.

How are arrays handled?

Element shapes are merged across every element of the array, so a field present in only one element still appears in the combined shape for that path.

Can it tell me which fields are optional in the live API?

No. Two samples show what those two responses happened to contain. A field missing from one sample may still be required in production, so read the diff as evidence and not as a schema.

Which file formats can I upload?

JSON or JSONL, exactly two response samples per job.