Command-line and Go package to compare and detect breaking changes in OpenAPI specs.

docker run --rm -t tufin/oasdiff changelog https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test5.yaml

• Detect breaking changes
• OpenAPI diff in YAML, JSON, Text/Markdown or HTML
• Display a user-friendly changelog of all important API changes
• Run from Docker
• Embed in your go program
• OpenAPI diff of local files system or remote files over http/s
• Compare specs in YAML or JSON format
• Compare two collections of specs
• Comprehensive diff including all aspects of OpenAPI Specification: paths, operations, parameters, request bodies, responses, schemas, enums, callbacks, security etc.
• API deprecation
• Multiple versions of the same endpoint
• Merge allOf schemas
• Path prefix modification
• Path parameter renaming
• Excluding certain kinds of changes
• Excluding endpoints
• Extending breaking-changes with custom checks
• Localization: display breaking-changes and changelog messages in English or Russian (please contribute support for your language)

go install github.com/tufin/oasdiff@latest

brew tap tufin/homebrew-tufin
brew install oasdiff

Copy binaries from latest release

• GitHub Action
• Cloud Service
• OpenAPI Sync: Get notified when an API provider breaks the API

oasdiff diff data/openapi-test1.yaml data/openapi-test2.yaml

The default diff output format is YAML.
No output means that the diff is empty, or, in other words, there are no changes.

oasdiff diff data/openapi-test1.yaml data/openapi-test2.yaml -f text

The Text/Markdown diff report provides a simplified and partial view of the changes.
To view all details, use the default format: YAML.
If you'd like to see additional details in the text/markdown report, please submit a feature request.

oasdiff diff data/openapi-test1.yaml data/openapi-test2.yaml -f html 

The HTML diff report provides a simplified and partial view of the changes.
To view all details, use the default format: YAML.
If you'd like to see additional details in the HTML report, please submit a feature request.

oasdiff diff https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml -f text

oasdiff breaking https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

oasdiff breaking https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml -f yaml

oasdiff breaking "data/composed/base/*.yaml" "data/composed/revision/*.yaml" -c

oasdiff breaking "data/composed/base/*.yaml" "data/composed/revision/*.yaml" -c -o ERR

oasdiff diff https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml -f text -o

oasdiff changelog https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

oasdiff diff https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml -f text -p "/api"

Filters are applied recursively at all levels. For example, if a path contains a callback, the filter will be applied both to the path itself and to the callback path. To include such a nested change, use a regular expression that contains both paths, for example -filter "path|callback-path"

oasdiff diff https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml -f text --filter-extension "x-beta"

Notes:

1. OpenAPI Extensions can be defined both at the path level and at the operation level. Both are matched and excluded with this flag.
2. If a path or operation has a matching extension only in one of the specs, but not in the other, it will appear as Added or Deleted.

oasdiff diff data/openapi-test1.yaml data/openapi-test3.yaml --exclude-elements description,examples -f text

oasdiff summary https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

To run with docker just replace the oasdiff command by docker run --rm -t tufin/oasdiff, for example:

docker run --rm -t tufin/oasdiff diff https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml -f text

docker run --rm -t tufin/oasdiff breaking https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

docker run --rm -t -v $(pwd)/data:/data:ro tufin/oasdiff diff /data/openapi-test1.yaml /data/openapi-test3.yaml

Replace $(pwd)/data by the path that contains your files.
Note that the spec paths must begin with /.

oasdiff is also available a service. See: https://github.com/oasdiff/oasdiff-service

The default diff output format, YAML, provides a full view of all diff details.
Note that no output in the YAML format signifies that the diff is empty, or, in other words, there are no changes.
Other formats: text, markdown, and HTML, are designed to be more user-friendly by providing only the most important parts of the diff, in a simplified format.
The JSON format works only with -exclude-elements endpoints and is intended as a workaround for YAML complex mapping keys which aren't supported by some libraries (see comment at end of next section for more details). If you wish to include additional details in non-YAML formats, please open an issue.

OpenAPI Specification has a hierarchical model of Paths and Operations (HTTP methods).
oasdiff respects this hierarchy and displays a hierarchical diff with path changes: added, deleted and modified, and within the latter, "modified" section, another set of operation changes: added, deleted and modified. For example:

paths:
    deleted:
        - /register
        - /subscribe
    modified:
        /api/{domain}/{project}/badges/security-score:
            operations:
                modified:
                    GET:

oasdiff also outputs an alternate simplified diff per "endpoint" which is a combination of Path + Operation, for example:

endpoints:
    deleted:
        - method: POST
          path: /subscribe
        - method: POST
          path: /register
    modified:
        ?   method: GET
            path: /api/{domain}/{project}/badges/security-score
        :   tags:
                deleted:
                    - security

The modified endpoints section has two items per key, method and path, this is called a complex mapping key in YAML.
Some YAML libraries don't support complex mapping keys:

• python PyYAML: see Tufin#94 (comment)
• golang gopkg.in/yaml.v3 fails to unmarshal the oasdiff output. This package offers a solution: https://github.com/tliron/yamlkeys

When using output format json, oasdiff excludes endpoints automatically.

Composed mode compares two collections of OpenAPI specs instead of a pair of specs in the default mode. The collections are specified using a glob. This can be useful when your APIs are defined across multiple files, for example, when multiple services, each one with its own spec, are exposed behind an API gateway, and you want to check changes across all the specs at once.

Notes:

1. Composed mode compares only paths and endpoints, other resources are compared only if referenced from the paths or endpoints.
2. Composed mode doesn't support Path Prefix Modification
3. Learn more about how oasdiff matches endpoints to each other

Sometimes paths prefixes need to be modified, for example, to create a new version:

• /api/v1/...
• /api/v2/...

oasdiff allows comparison of API specifications with modified prefixes by stripping and/or prepending path prefixes.
In the example above you could compare the files as follows:

oasdiff diff original.yaml new.yaml --strip-prefix-base /api/v1 --prefix-base /api/v2

or

oasdiff diff original.yaml new.yaml --strip-prefix-base /api/v1 --strip-prefix-revision /api/v2

Note that stripping precedes prepending.

Sometimes developers decide to change names of path parameters, for example, in order to follow a certain naming convention.
See this to learn more about how oasdiff supports path parameter renaming.

You can use the --exclude-elements flag to exclude certain kinds of changes:

• Use --exclude-elements examples to exclude Examples
• Use --exclude-elements description to exclude description fields
• Use --exclude-elements title to exclude title fields
• Use --exclude-elements summary to exclude summary fields
• Use --exclude-elements endpoints to exclude the endpoints diff

You can ignore multiple elements with a comma-separated list of excluded elements as in this example.
Note that Extensions are always excluded from the diff.

You can filter endpoints in two ways:

1. By path name: use the --match-path option to exclude paths that don't match the given regular expression, see example
2. By extension: use the --filter-extension option to exclude paths and operations with an OpenAPI Extension matching the given regular expression, see example

diff.Get(&diff.Config{}, spec1, spec2)

• diff
• breaking changes

oasdiff expects OpenAPI References to be resolved.
References are normally resolved automatically when you load the spec. In other cases you can resolve refs using Loader.ResolveRefsIn.

1. OpenAPI 3.1 support: see Tufin#52

If you have other ideas, please let us know.

The oasdiff tool collects data in order to help us, the development team, understand how it is being used and what we can to do to continue improving it.
We use this data in compliance with our privacy policy.
To disable telemetry, add the environment variable: OASDIFF_NO_TELEMETRY=1

This project relies on the excellent implementation of OpenAPI 3.0 for Go: kin-openapi.