How much more efficient is the Rust version?

OpenAI says the Rust service is 6x more CPU efficient and 15x more memory efficient than the Python version, with significantly lower average and tail latencies.

Who did the rewrite and how long did it take?

OpenAI says just 2 engineers, Codex, and GPT-5.5 rewrote the entire service in Rust in Q2 2026.

What happens to the Python version?

OpenAI says it will deprecate Python entirely in the coming weeks, after the Rust service reached 95% of production requests.

Large Language ModelsAI Coding AssistantsOpenAI BlogSep 11, 2026Sep 12, 2026, 04:00 JST

OpenAI's Habitat storage rewritten in Rust, 6x more CPU efficient

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3 Key Points

What happened
OpenAI said it rewrote its Habitat storage platform from Python to Rust in Q2 2026 with 2 engineers, Codex, and GPT-5.5. The Rust service handles 95% of production requests and is 6x more CPU efficient.
Why it matters
Habitat now handles over 70 million requests per second for more than 1 billion weekly users across almost 40 regions, up from a single-database Python library two years ago.
What to watch
OpenAI says it will deprecate Python entirely in the coming weeks; the test is whether the Rust service keeps the same reliability. Watch the promised future post on multi-tenancy and Azure Cosmos DB scaling.

WHO IT HITSEngineering leaders at companies running large-scale online services get a concrete data point on rewriting performance-critical Python services in Rust, with OpenAI reporting 6x CPU and 15x memory efficiency gains. OpenAI's own product teams are the immediate beneficiaries, since the platform handles 95% of production requests.

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Context & Analysis

Habitat began in mid-2024 as a simple Python client-side library that interacted with ChatGPT's main server and Azure Cosmos DB. It saw rapid adoption among OpenAI product engineers, with no central push away from self-serve Postgres and Azure Cosmos DB. By the middle of 2025, it had reached its limits as a client-side implementation, as backward-compatible protocol changes had become infeasible and coordinating deployments across dozens of services took days.

OpenAI then pulled Habitat into its own service, accepting Python's performance trade-offs as a "strategic incursion of technical debt" to unblock product developers and achieve platform stability. The team made a calculated wager that rapid advancement of OpenAI's own coding models would simplify an eventual migration off Python, and OpenAI says that bet proved correct. In Q2 2026, with just 2 engineers, Codex, and GPT-5.5, the entire service was rewritten in Rust.

The outcome now hinges on whether the Rust service can maintain the reliability OpenAI says it needs while handling 95% of production requests, and whether the promised deprecation of Python proceeds as stated. OpenAI says it will share more learnings in a future blog, including on multi-tenancy reliability and scaling Azure Cosmos DB.

FAQ

How much more efficient is the Rust version?: OpenAI says the Rust service is 6x more CPU efficient and 15x more memory efficient than the Python version, with significantly lower average and tail latencies.
Who did the rewrite and how long did it take?: OpenAI says just 2 engineers, Codex, and GPT-5.5 rewrote the entire service in Rust in Q2 2026.
What happens to the Python version?: OpenAI says it will deprecate Python entirely in the coming weeks, after the Rust service reached 95% of production requests.

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