Launch HN: Relace (YC W23) – Models for fast and reliable codegen

Summary

Hey HN community! We're Preston and Eitan, and we're building Relace (https://relace.ai). We're trying to make building code agents easy and cheap.Here’s an example of our apply model vs. whole file edits: https://youtu.be/J0-oYyozUZwBuilding reliable code agents is hard. Beyond simple prototypes, any app with code generation in production quickly runs into two problems -- how do you reliably apply diffs, and how do you manage codebase context?We're focused on solving these two problems at order-of-magnitude lower price and latency.Our first model that we released, in February, is the Fast Apply model -- it merges code snippets with files at 4300 tok/s. It is more reliable (in terms of merge errors) than Sonnet, Qwen, Llama, or any other model at this task. Each file takes ~900ms and gives an instantaneous user experience, as well as saving ~40% on Claude 4 output tokens.Our second model focuses on retrieval. For both vibe-coded and enterprise codebases, retrieving only the files relevant to a user request saves both on SoTA input token cost and reduces the number of times code agents need to view files. Our reranker (evals below) can scan a million-line codebase in ~1-2s, and our embedding model outperforms any other embedding model for retrieval as evaluated on a corpus of Typescript/React repositories.There are many different ways to build coding agents, but being able to edit code reliably and retrieve the most relevant parts of the codebase is going to be a foundational issue. We're excited to be building ways to make it more accessible to millions of users who don't want to spend $$$ on Claude.These models are used in production, millions of times per week. If you've used Lovable, Create.xyz, Magic Patterns, Codebuff, Tempo Labs then you've used us!Here's a link to try it out: https://app.relace.ai, and here are our docs: https://docs.relace.ai.We've opened up free access for prototyping on our website to everyone, and the limits should be enough for personal ...