Case Study: Letgo achieves flexible, secure API delivery with KrakenD

Second Hand Selling Application Using a Gateway per Device

Letgo, a fast-growing secondhand buying and selling app with both desktop and native mobile experiences, needed a way to support different UI teams and device-specific needs while keeping a consistent API contract across changing backends. Using KrakenD API Gateway, Letgo could manage separate gateway clusters per client and enforce authentication, authorization, and token revocation at the API layer.

KrakenD implemented automatic aggregation and filtering so each team received a simple, customized API for its device, while JWT validation and permission checks helped block illegitimate users without affecting backends. Letgo also used KrakenD’s bloomfilter for massive token rejection with low memory use, handling 100 million tokens in about 0.5 GB of RAM with constant-time lookups and an extremely low false-positive rate, enabling fast, distributed, stateless performance.

Letgo