How to generate API clients from OpenAPI specs

· Category: API & REST

Short answer

OpenAPI Generator produces client libraries, server stubs, and documentation from an OpenAPI specification, reducing manual boilerplate and ensuring consistency.

Steps

  1. Write or export a valid OpenAPI specification for your API.
  2. Install OpenAPI Generator CLI or use the online generator.
  3. Select the target language and configure package names and model prefixes.
  4. Run the generator to emit source code for models and API clients.
  5. Integrate the generated code into your application and regenerate when the spec changes.

Tips

  • Automate generation in CI/CD so client code never drifts from the spec.
  • Customize templates to match your coding standards and naming conventions.
  • Publish generated packages to internal artifact repositories.
  • Validate the spec with linting before generation to catch errors early.

Common issues

  • Generated models lacking validation logic beyond type checking.
  • Complex polymorphism in specs producing confusing inheritance hierarchies.
  • Manual edits to generated code being overwritten on regeneration.
  • Version mismatches between the spec and the deployed API.

Example

curl -X GET https://api.example.com/users   -H "Accept: application/json"   -H "Authorization: Bearer $TOKEN"

This curl command demonstrates a standard GET request with headers for content negotiation and bearer token authentication.