What tools can I use to test for 401 errors?

You can use various tools: 1) Postman: A popular API client that allows you to manually send requests and examine responses. 2) curl: A command-line tool for transferring data with URLs, useful for testing API endpoints. 3) Insomnia: Another API client with similar features to Postman. 4) Browser Developer Tools: Inspect network requests and responses directly within your browser. 5) API testing frameworks (e.g., pytest with requests in Python).