CodSpeed

CodSpeed is a continuous performance testing and optimization platform that integrates directly into CI/CD workflows to catch performance regressions before they ship. It supports multiple languages and benchmark frameworks, delivers results as PR comments and status checks, and uses CPU simulation to bring measurement variance below 1%. The core CLI is open source under the Apache License 2.0, while the cloud dashboard and hosted runner infrastructure are commercial offerings.

What It Is

CodSpeed sits between your benchmark suite and your pull request workflow. Developers write benchmarks using familiar frameworks — pytest, criterion, vitest, divan, google-benchmark, or Go's built-in testing package — and CodSpeed wraps those runs with instrumentation that filters out system noise and produces stable, comparable results. The platform then surfaces performance changes as PR comments, blocks merges that exceed configured thresholds, and provides differential flamegraphs to pinpoint which lines of code got slower.

How the Instrumentation Works

CodSpeed offers three measurement modes, each suited to different workloads:

• CPU Simulation: Simulates CPU behavior to achieve less than 1% variance regardless of system load. Hardware-agnostic and automatically generates flamegraphs. Best for CPU-intensive code and CI regression detection.
• Walltime: Measures real-world execution time including I/O, system calls, and multi-threading effects. Recommended for API tests and I/O-heavy workloads, and works best on CodSpeed's hosted Macro Runners rather than standard cloud VMs.
• Memory: Tracks heap allocations using eBPF profiling, covering peak usage, allocation count, and allocation size. Supported for Rust and C/C++ with libc, jemalloc, or mimalloc.

Setup Path

CodSpeed provides two setup routes. The AI Wizard analyzes a connected repository, detects or creates benchmark files, generates a CI workflow configuration, and opens a pull request — requiring no manual configuration. The manual path involves installing a language-specific harness (e.g., pip install pytest-codspeed), writing benchmarks with the appropriate marker or framework, and adding a GitHub Actions or GitLab CI workflow that calls the CodSpeedHQ/action. The CLI can be installed via a single shell command and officially supports Ubuntu 20.04/22.04/24.04 and Debian 11/12.

Language and CI Integrations

CodSpeed provides first-class harness integrations across:

• Python — pytest plugin (pytest-codspeed)
• Rust — divan, criterion.rs, bencher
• Node.js — vitest, tinybench, benchmark.js
• C/C++ — google-benchmark
• Go — built-in testing package
• Zig — community-maintained harness

CI integrations cover GitHub Actions (via the official CodSpeedHQ/action), GitLab CI, and Buildkite. The platform also supports a codspeed.yml configuration file for defining multiple benchmark targets with per-benchmark options like warmup time and max rounds.

Update: v4.18.1

The latest CLI release is v4.18.1, published on June 24, 2026. The GitHub repository, written primarily in Rust, was last pushed on June 30, 2026, indicating active development. The project has accumulated over 210 stars and 24 forks since its creation in November 2023. Recent documentation highlights the AI Wizard as a new automated setup path, and the platform page lists Go support as a current language integration alongside the established Python, Rust, Node.js, and C/C++ support.