BuildFetch Cache vs Harmonia

BuildFetch Cache is a remote cache platform intended to reduce build times and CI costs across build systems. It lists native support for Bazel, Gradle, Maven, Sbt, Buck2, Moon, Buildbarn, Ccache, Sccache, Go, Nx, and Turborepo; its listed compiler and language support includes C, C++, Rust, Go, Kotlin, Java, TypeScript, Scala, Assembly, CUDA, Objective-C, Objective-C++, and AMD ROCm HIP. Remote cache outputs can be shared across engineer workstations, CI, and AI agent environments. For Bazel, it supports both gRPC and HTTP remote cache APIs. BuildFetch uses NVMe for ephemeral cache storage and SSD for persistent storage, and its dashboard shows throughput, tail latency, request volume, and storage usage. Scoped project tokens can set read-only or read-write access. The product is offered through BuildFetch Cloud and can also be deployed in Custom Cloud or on-premise Kubernetes environments. The free Open Source plan has caps of 20GB fast cache storage, 50GB network traffic, and 100,000 cache requests, with 45 days LRU retention; those resource caps cannot be exceeded. Paid plans start at $55 a month, and a 45-day trial is listed for Custom. BuildFetch says data is encrypted in transit and at rest.

Harmonia is free, open-source software for serving a Nix store as a binary cache over HTTP. Written in Rust for Linux self-hosting, it supports HTTP range requests for NAR streaming and streaming build logs. The /serve// endpoint can provide package contents and discover index.html to serve websites directly from the Nix store. Harmonia can transparently compress content with zstd and provide TLS when no frontend web server is used. Documentation covers a NixOS module and nginx HTTPS frontend configuration for a public cache. Narinfo signing is disabled unless private signing-key paths are supplied. Prometheus metrics are available at /metrics, with a Grafana dashboard included in the repository. Since version 3.1.0, metadata is read directly from db.sqlite without a nix-daemon connection. Version 3.3.0 adds harmonia-gc for removing store garbage while nix-daemon builds. It uses the MIT License.