Rewrite: 6 real scaling case studies
6 of the 73 engineering write-ups in our database are tagged with the technique "rewrite". They come from 6 companies (Cloudflare, Datadog, Discord, Dropbox, Figma and 1 more) and were published between 2018 and 2026 (1 undated). Stack that shows up most often in these stories: Rust (6) and Python (2). 2 of the 6 state concrete scale numbers, for example "70 million+ requests/sec" (OpenAI). Each card below links to our short summary and the original post.
Rapidly scaling online storage to serve over 1 billion ChatGPT users
OpenAI's Habitat storage platform grew from a Python client library over Cosmos DB into a central service handling 70M+ requests per second. The team ran many low-concurrency Python processes to keep asyncio delay down, switched aiohttp connection reuse from LIFO to FIFO to stop a metastable failure, used Envoy for connection fan-in, kept a deliberately simple NoSQL API, then rewrote the service in Rust.
Timeseries indexing at scale
Datadog redesigned its timeseries indexing to handle a large jump in ingested data.
How we built Pingora, the proxy that connects Cloudflare to the Internet
Cloudflare replaced Nginx with Pingora, a Rust proxy that reuses connections better and needs less CPU and memory.
Why Discord is switching from Go to Rust
Discord rewrote its Read States service from Go to Rust to get rid of garbage-collection latency spikes in a large in-memory cache.
How Mozilla's Rust dramatically improved our server-side performance
Figma rewrote its multiplayer server in Rust to cut latency and memory use as documents and users grew.
Rewriting the heart of our sync engine
Dropbox rewrote its desktop sync engine in Rust with a new data model built for correctness and testability.