Gradient

Nix-CI for Teams. Every flake built once, on any machine, cached for everyone.

Features

• Git Host Integration

  Building on push and pull request from GitHub, Gitea / Forgejo and GitLab. Status checks sent back.

• Build Before Pushing

  Uncommitted changes built on the CI workers with gradient build, no local Nix needed.

• Built-in Binary Cache

  Per-project caches with S3 storage, signing and sharing between projects.

• Scales With Workers

  Evaluation and building both on workers. More capacity with every added machine.

• MCP Server

  Logs, evaluations and failed builds, readable by any AI assistant.

• Pull Deployment

  Machines fetch and switch to their latest built NixOS configuration on their own.

• Declarative Setup

  Users, projects, caches and workers as NixOS options, validated at build time.

• SSO and Teams

  OIDC login, SCIM provisioning, roles and invitations per project and cache.

Compared to Hydra and GitHub Actions

	Hydra	GitHub Actions + Cachix	Gradient
Build start	After the whole evaluation	After the whole evaluation	While the evaluation is still running
Evaluation	On the server, limited by one machine	Inside each job, limited by the runner	On workers, scales with them
Evaluation speed	Fast	Slow	Fastest available
Building Order	Round Robin	single Worker	Maximum CPU Load, Minimal Network Traffic, Memory / OOM aware
Import from derivation (IFD)	Not activly supported	Built by the runner inside the job	Built on the workers as shared builds, cached and logged like any build
Wildcard Support	No	No	Yes
Nix store	Kept on the server and builders	Empty on every job; each job downloads its closure again	Kept on the workers between builds
Build outputs	Everything through the server	Pushed from the runner to Cachix	Large outputs go from worker straight to S3
Server host	Needs a writable Nix store	Hosted by GitHub	Needs no Nix store, Micro-VM ready
Heavy builds	Static machine list with speed factors	Fixed runner sizes	Scoring system places them by predicted memory, learned from past builds
Remote building over SSH	Not available	Not available	ssh-ng:// store for nixos-rebuild --build-host and nix copy straight to the CI workers
Private caches	One store for the whole instance	Free plan: 5 GB, filled quickly by full closures	Per-project caches with access control, on own S3 or disk storage
Sign-in	Local accounts, LDAP, OIDC with roles for the whole instance	GitHub accounts	OIDC with provider groups mapped to roles per project, SCIM provisioning
Integrations	Minimal JSON API	GitHub only	REST API, webhooks, Git Integrations and MCP server
Web UI	Server-rendered pages	GitHub job logs	Responsive UI with live log streaming
Runners	Not available	builtin	Soon; On Roadmap
Stars		-

Public Binary Cache

Pre-built Gradient packages are available from the public cache.

URL:        https://public.gradient.ci/cache/main
Public Key: public.gradient.ci-main:qmxRE+saUvhNa3jqaCMWje+feVU77TjABchZrPGf7A8=

Links

• Source code: https://github.com/wavelens/gradient
• API reference: Swagger UI
• NixOS options search: https://wavelens.github.io/gradient-search
• Chat: #gradient-ci:matrix.org

Project

• Support: community help, long-term and commercial support.
• Security Policy: private vulnerability reports.
• Privacy: no telemetry, all data self-hosted.
• Governance: roles, maintainers and decisions.
• Accessibility: web UI support and barrier reports.

Get started Try the public instance

The developer of Gradient is Wavelens GmbH. Gradient is available under the AGPL-3.0-only license.