Building Docker images in CI today is slow. CI runners are ephemeral, so they must save and load the cache for every build. They have constrained resources, with limited CPUs, memory, and disk space. And they do not support native Arm or multi-platform container builds, and instead require emulation.

Over 4 years of working together, we spent countless hours optimizing and reoptimizing Dockerfiles, managing layer caching in CI, and maintaining custom runners for multi-platform images. We were working around the limitation of multi-platform builds inside of GitHub Actions via QEMU emulation when we thought "wouldn't it be nice if someone just offered both an Intel and Arm builder for Docker images without having to run all that infrastructure ourselves". Around January of 2022 we started working on Depot, designed as the service we wished we could use ourselves.

Depot provides managed VMs running BuildKit, the backing build engine for Docker. Each VM includes 16 CPUs, 32GB of memory, and a persistent 50GB SSD cache disk that is automatically available across builds—no saving or loading of layer cache over the network. We launch both native Intel and native Arm machines inside of AWS. This combination of native CPUs, fast networks, and persistent disks significantly lowers build time — we’ve seen speedups ranging from 2x all the way to 20x. We have customers with builds that took three hours before that now take less than ten minutes.

We believe that today we are the fastest hosted build service for Docker images, and the only hosted build service offering the ability to natively build multi-platform Docker images without emulation.

We did a Show HN last September: https://news.ycombinator.com/item?id=33011072. Since then, we have added the ability to use Depot in your own AWS account; added support for Buildx bake; increased supported build parallelism; launched an eu-central-1 region; switched to a new mTLS backend for better build performance; simplified pricing and added a free tier; and got accepted into YC W23!

Depot is a drop-in replacement for `docker buildx build`, so anywhere you are running `docker build` today, you replace it with `depot build` and get faster builds. Our CLI is wrapping the Buildx library, so any parameters you pass to your Docker builds today are fully compatible with Depot. We also have a number of integrations that match Docker integrations inside of CI providers like GitHub Actions.

We’re soon launching a public API to programmatically build Docker images for companies that need to securely build Docker images on behalf of their customers.

You can sign up at https://depot.dev/sign-up, and we have a free tier of 60 build minutes per month. We would love your feedback and look forward to your comments!