# Puneet Khanduri - Diffy: Testing Services Without Writing Tests (Highlights) ![rw-book-cover|256](https://readwise-assets.s3.amazonaws.com/static/images/article1.be68295a7e40.png) ## Highlights - Today, we’re excited to release Diffy, an open-source tool that automatically catches bugs in Apache Thrift and HTTP-based services. https://github.com/opendiffy/diffy - Diffy finds potential bugs in your service by running instances of your new and old code side by side. - It then compares the responses - Diffy acts as a proxy which accepts requests drawn from any source you provide and multicasts each of these requests to three different service instances: