C3X vs Infracost

Feature comparison

Where Infracost wins

Infracost has been in the market since 2019 and has built up a substantial ecosystem. Areas where it's still the right pick:

• OPA/Rego policy integration: Infracost Cloud's policy engine is mature; rules can block PRs based on complex conditions. C3X has basic budget gating; deeper policy is on the roadmap.
• Dedicated enterprise support: Infracost Cloud includes SLAs, response time guarantees, and dedicated engineers. C3X support is via community and commercial partners.
• Cloud dashboard: Infracost Cloud's dashboard aggregates costs across PRs, repos, and orgs. Useful for FinOps teams that want a central view across many projects.

Where C3X wins

C3X was built differently from the start, optimizing for the most-asked-for things in the original Infracost open-source issues:

• No API key for public endpoint: The pricing API at pricing.c3x.dev is free to use without authentication. Useful for proofs of concept and small teams.
• Free CloudFormation: CloudFormation support is gated behind Infracost's paid tier. In C3X, it's free.
• Free cost recommendations: Recommendations (right-sizing, gp2-to-gp3, etc.) are part of Infracost Cloud (paid). C3X includes them in the OSS CLI.
• Fully offline mode: A single docker-compose spins up the pricing API with no external dependencies after data load. Required for air-gapped environments (GovCloud, IL5/IL6, financial sector).
• No vendor lock-in: Apache 2.0 throughout. The pricing API, CLI, and recommendations are all open. If C3X disappeared tomorrow, your team could continue running from a fork.

Migration: command translation

For most workflows, migration is mechanical. The CLI command structure is similar:

Migration: GitHub Actions

The Infracost GitHub Action and C3X GitHub Action have similar structures. Replacing the action is typically 5-10 lines of YAML:

# Before (Infracost):
- uses: infracost/actions/setup@v3
  with:
    api-key: ${{ secrets.INFRACOST_API_KEY }}
- run: infracost breakdown --path . --format json --out-file infracost.json
- uses: infracost/actions/comment@v3
  with:
    path: infracost.json

# After (C3X):
- uses: c3xdev/c3x-action@v1
- run: c3x estimate --diff --format=github-comment > c3x.md
- uses: actions/github-script@v7
  with:
    script: |
      const fs = require('fs')
      github.rest.issues.createComment({
        issue_number: context.issue.number,
        owner: context.repo.owner,
        repo: context.repo.repo,
        body: fs.readFileSync('c3x.md', 'utf8')
      })

Pricing data source

Both tools pull from the same upstream sources but expose different public APIs:

• AWS: Bulk pricing API (offers.api.aws/v1.0)
• Azure: Retail Prices API (prices.azure.com)
• GCP: Cloud Billing Catalog API

C3X's pricing API (pricing.c3x.dev) is free to query without authentication. Infracost's cloud-pricing-api is also self-hostable but the SaaS endpoint requires an API key. For details on running the pricing API yourself, see self-hosting the pricing API on a €4 VPS.

When to keep Infracost

1. You've already paid for Infracost Cloud and use OPA/Rego policies that don't have C3X equivalents.
2. Your enterprise contract requires named-engineer SLAs with the tool vendor.
3. You use Infracost-specific integrations (Atlantis with Infracost policy callbacks, etc.) that haven't been ported.

When to switch to C3X

1. You're hitting Infracost's paid feature gates (CloudFormation, recommendations).
2. You need fully offline mode for regulated environments.
3. Your organization prefers open-source-only infrastructure.
4. You want to avoid SaaS lock-in for cost-related tooling.
5. Budget is a concern and the free tier doesn't cover your usage.

FAQ

Related reading

• Long-form post on the open-source alternative angle
• How we run the pricing API on a €4 VPS
• Budget guardrails in CI: blocking PRs that exceed cost limits