Optimize code performance and catch regressions early.

Get Started · Documentation

Key features

• 🎯 <1% variance in measurements using CPU simulation - no more flaky benchmarks.
• 🔥 Differential flamegraphs to pinpoint exactly what got slower, commit by commit.
• 💬 PR comments & status checks showing performance impact directly in your workflow.
• 🛡️ Merge protection to block PRs that degrade performance beyond your threshold.
• 🐍 Multi-language support for Python, Rust, Node.js, Go, C/C++ and more.
• 🏠 Run locally or in CI - works on your machine and integrates with GitHub Actions, GitLab CI, and more.
• 🔌 Plug your existing benchmarks in less than 5 minutes - works with pytest, vitest, criterion, and more.

Installation

curl -fsSL https://codspeed.io/install.sh | bash

Note

The CodSpeed CLI officially supports Ubuntu 20.04, 22.04, 24.04 and Debian 11, 12. Other Linux distributions may work, but are not officially supported.

Quick Start

First, authenticate to keep your benchmark results linked to your CodSpeed account:

codspeed auth login

The simplest way to get started is to benchmark any executable program directly:

# Benchmark a single command
codspeed exec -- ./my-binary --arg1 value

# Benchmark a script
codspeed exec -- python my_script.py

# Benchmark with specific instrument
codspeed exec --mode walltime -- node app.js

This approach requires no code changes and works with any executable. CodSpeed will measure the performance provide the instrument results.

Deeper integration with harnesses using codspeed run

For more control and integration with your existing benchmark suite, you can use language-specific harnesses. This allows you to:

• Define multiple benchmarks and keep them versioned in your codebase
• Scope benchmarks to specific functions or modules
• Integrate with existing benchmark suites (pytest, criterion, vitest, etc.)

# Using the Rust harness with criterion
codspeed run cargo codspeed run

# Using the Python harness with pytest
codspeed run pytest ./tests --codspeed

# Using the Node.js harness with vitest
codspeed run pnpm vitest bench

These harnesses provide deeper instrumentation and allow you to write benchmarks using familiar testing frameworks.

Languages Integrations

CodSpeed provides first-class integrations for multiple languages and frameworks:

Language	Repository	Supported Frameworks
Rust	codspeed-rust	divan, criterion.rs, bencher
C/C++	codspeed-cpp	google-benchmark
Python	pytest-codspeed	pytest plugin
Node.js	codspeed-node	vitest, tinybench, benchmark.js
Go	codspeed-go	builtin testing package integration
Zig (community)	codspeed-zig	custom

Need to bench another language or framework? Open an issue or let us know on Discord!

CLI Harness: codspeed.yml configuration

The CLI also offers a built-in harness that allows you to define benchmarks directly.

You can define multiple codspeed exec benchmark targets and configure options in a codspeed.yml file. This is useful when you want to benchmark several commands with different configurations.

Create a codspeed.yml file in your project root:

# Global options applied to all benchmarks
options:
  warmup-time: "0.2s"
  max-time: 1s

# List of benchmarks to run
benchmarks:
  - name: "Fast operation"
    exec: ./my_binary --mode fast
    options:
      max-rounds: 20

  - name: "Slow operation"
    exec: ./my_binary --mode slow
    options:
      max-time: 200ms

  - name: "Script benchmark"
    exec: python scripts/benchmark.py

Then run all benchmarks with:

codspeed run --mode walltime

Tip

For more details on configuration options, see the CLI documentation.

Performance Instruments

CodSpeed provides multiple instruments to measure different aspects of your code's performance. Choose the one that best fits your use case:

CPU Simulation

Simulates CPU behavior for <1% variance regardless of system load. Hardware-agnostic measurements with automatic flame graphs.

Best for: CPU-intensive code, CI regression detection, cross-platform comparison

codspeed exec --mode simulation -- ./my-binary

Memory

Tracks heap allocations (peak usage, count, allocation size) with eBPF profiling.

Best for: Memory optimization, leak detection, constrained environments

Supported: Rust, C/C++ with libc, jemalloc, mimalloc

codspeed exec --mode memory -- ./my-binary

Walltime

Measures real-world execution time including I/O, system calls, and multi-threading effects.

Best for: API tests, I/O-heavy workloads, multi-threaded applications

codspeed exec --mode walltime -- ./my-api-test

Warning

Using the walltime mode on traditional VMs/Hosted Runners will lead to inconsistent data. For the best results, we recommend using CodSpeed Hosted Macro Runners, which are fine-tuned for performance measurement consistency. Check out the Walltime Instrument Documentation for more details.

Tip

For detailed information on each instrument, see the Instruments documentation.

Usage In CI environments

Running CodSpeed in CI allows you to automatically detect performance regressions on every pull request and track performance evolution over time.

GitHub Actions

We recommend using our official GitHub Action: @CodSpeedHQ/action.

Here is a sample .github/workflows/codspeed.yml workflow for Python:

name: CodSpeed Benchmarks

on:
  push:
    branches:
      - "main" # or "master"
  pull_request:
  workflow_dispatch:

permissions:
  contents: read
  id-token: write

jobs:
  benchmarks:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      # Set up your language/environment here
      # For Python:
      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"
      - run: pip install -r requirements.txt

      # Run benchmarks with CodSpeed
      - uses: CodSpeedHQ/action@v4
        with:
          mode: instrumentation
          run: pytest tests/ --codspeed

GitLab CI

Here is a sample .gitlab-ci.yml configuration for Python:

workflow:
  rules:
    - if: $CI_PIPELINE_SOURCE == 'merge_request_event'
    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH

codspeed:
  stage: test
  image: python:3.12
  id_tokens:
    CODSPEED_TOKEN:
      aud: codspeed.io
  before_script:
    - pip install -r requirements.txt
    - curl -fsSL https://codspeed.io/install.sh | bash -s -- --quiet
  script:
    - codspeed run --mode simulation -- pytest tests/ --codspeed

Tip

For more CI integration examples and advanced configurations, check out the CI Integration Documentation.