ModernCI and Namespace
Namespace sells fast compute for CI: GitHub Actions runners that you adopt by changing runs-on to a Namespace profile, cache volumes that persist across runs, remote Docker builders and devboxes. ModernCI is a different layer: a self-hosted CI server and merge queue that decides what runs, cancels stale work, merges green pull requests and sends failures back to agents. If you want faster, well-cached runners for the workflows you have, Namespace is the smaller change. If the queue of pull requests waiting to be tested and merged is the problem, that's what ModernCI addresses.
Marks: live is in release 0.4.28 on main; planned is decided, not built. Namespace facts are from namespace.so/pricing, Namespace for GitHub Actions and Namespace compute, read 2026-10-13.
What Namespace is (from its public pages)
- Adoption: create a runner profile, then use
runs-on: namespace-profile-<name>. You choose the OS (Linux amd64 or arm64, Windows, macOS) and a shape you can change later. - Cache volumes: they persist across runs and transparently cache container images, toolchain downloads and action downloads.
nscloud-cache-actioncovers framework caches and arbitrary paths. Caches are shared by every user of a profile and can be made writable only from chosen branches. - Price (Linux x64, per minute, prepaid / overage): 2 vCPU 8 GB $0.004 / $0.006; 4 vCPU 16 GB $0.008 / $0.012; 8 vCPU 32 GB $0.016 / $0.024; 16 vCPU 64 GB $0.032 / $0.048.
- Plans: Developer $0 (pay per use), Team $100 a month (100,000 unit minutes), Business $250 a month (250,000), Enterprise custom.
- Limits: Linux concurrency of 32 / 64 / 160 vCPU on Developer / Team / Business, and a maximum instance duration of 3 h / 5 h / up to 24 h.
- Also: remote Docker builders, Bazel and Turborepo caches, devboxes, and an API and SDK for compute.
When Namespace is the better fit
- You want faster, cached GitHub Actions runs with a one-line change per job.
- You use Windows or macOS runners, or need Docker build acceleration.
- You don't want to run anything yourself.
When to consider ModernCI
- Agent pull requests pile up waiting to be tested and merged. ModernCI's merge queue merges the deepest green prefix of a batch and bisects a failing one. live
- Runs a newer push made pointless keep burning minutes. ModernCI cancels them per check, across pull requests. live
- Failures should go back to the coding agent that wrote the change, over MCP. live
- You need to self-host, or run with no outside service. live
Using both
ModernCI places checks on backends: your machine, ssh hosts, and Latchkey runners today, with EC2 and Hetzner Cloud planned. No Namespace backend exists. Namespace lists an API and SDK for compute; whether it can start a ModernCI job outside GitHub Actions hasn't been tested. With external checks planned, ModernCI's merge queue could use your Actions workflows, running on Namespace, as the result for the commit it tests.
Evidence
- Clean and incremental Rust build times, and cost per merged change, on matched shapes: measurement in progress. See benchmarks.
Limitations of ModernCI here
- In 0.4.28 one pull request's checks run one after another. Parallel checks are planned.
- No public download yet and no hosted service, whereas Namespace is hosted.
- No Windows backend, and no Docker build acceleration of its own.
See also: GitHub Actions, Blacksmith, facts.