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

Try it

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

Features

• Detect breaking changes
• Display a user-friendly changelog of all important API changes
• OpenAPI diff in YAML, JSON, Text/Markdown or HTML
• Run from Docker
• Embed in your go program
• OpenAPI diff of local files 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
• Merge common parameters
• Case-insensitive header comparison
• Path prefix modification
• Path parameter renaming
• Excluding certain kinds of changes
• Tracking changes to OpenAPI Extensions
• 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)

Install with Go

go install github.com/tufin/oasdiff@latest

Install on macOS with Brew

brew tap tufin/homebrew-tufin
brew install oasdiff

Install on macOS, Windows and Linux

Copy binaries from latest release

Wrappers

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

Usage Examples

OpenAPI diff of local files in YAML

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.

OpenAPI diff of local files in Text/Markdown

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.

OpenAPI diff of local files in HTML

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.

OpenAPI diff for remote files over http/s

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

Breaking changes

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

Breaking changes as 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

Breaking changes across multiple specs with globs

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

Fail with exit code 1 if any ERR-level breaking changes are found

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

Fail with exit code 1 if any change is found

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

OpenAPI changelog

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

OpenAPI diff for endpoints containing "/api" in the 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 -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"

Exclude paths and operations with extension "x-beta"

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.

Ignore changes to description and examples

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

Display change summary

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

OpenAPI Diff with Docker

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

Breaking changes with Docker

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

Comparing local files with Docker

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 /.

OpenAPI Diff, Breaking Changes and Changelog as a Service

Oasdiff is also available as a service.

Diff Output Formats

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.

Paths vs. Endpoints

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

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

Path Prefix Modification

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.

Path Parameter Renaming

Sometimes developers decide to change names of path parameters, for example, in order to follow a certain naming convention.
Oasdiff supports path parameter renaming by default.
Learn more about how oasdiff supports path parameter renaming.

Case-Insensitive Header Comparison

Header names comparison is normally case-sensitive.
To make this comparison case-insensitive, add the --case-insensitive-headers flag:

oasdiff diff data/header-case/base.yaml data/header-case/revision.yaml --case-insensitive-headers

Excluding Specific Kinds of Changes

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

• Use --exclude-elements examples to exclude Examples
• Use --exclude-elements extensions to exclude Extensions
• 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.

Excluding Specific Endpoints

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

OpenAPI Extensions

Oasdiff tracks changes to OpenAPI extensions by default. To disable this, see Excluding Specific Kinds of Changes.
The diff format for OpenAPI extensions conforms with JavaScript Object Notation (JSON) Patch, for example:

endpoints:
    modified:
        ?   method: POST
            path: /example/callback
        :   extensions:
                modified:
                    x-amazon-apigateway-integration:
                        - oldValue: "201"
                          value: "200"
                          op: replace
                          from: ""
                          path: /responses/default/statusCode
                        - oldValue: http://api.example.com/v1/example/callback
                          value: http://api.example.com/v1/example/calllllllllback
                          op: replace
                          from: ""
                          path: /uri

Notes for Go Developers

Embedding oasdiff into your program

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

Code Examples

• diff
• breaking changes

OpenAPI References

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.

Requests for enhancements

1. OpenAPI 3.1 support: see Tufin#52

If you have other ideas, please let us know.

Telemetry

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

Credits

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