CopilotChat

CopilotChat takes the test-driven development loop and gives it to a model. The workflow has three stages. First the developer defines test cases: concrete pairs of inputs and expected outputs, plus an optional description of the requirement in plain language. This specification is what the rest of the process is judged against, so the quality of the tests directly shapes the quality of the output.

Second, the large language model generates an implementation that aims to satisfy those cases. Third, CopilotChat itself acts as the validator. It runs the generated code against the test cases, and if any case fails it re-engages the model with the failure details, refining the implementation across successive rounds until every case passes. The result is code that comes with a built-in correctness argument rather than a hopeful first draft.

The interface supports multiple test case examples at once, and the site includes a ready-made demo that generates a JavaScript function from a described requirement, so you can see the whole define-generate-validate cycle without installing anything. The approach suits small, well-specified functions and utility logic where you can state expected behaviour precisely. Pricing is arranged directly with the provider.