cert-manager vs lego
A side-by-side comparison of two self-hosted reverse proxy & gateways options — licensing, setup difficulty, resource needs, and what each one replaces.
cert-manager
Automated TLS certificate management for Kubernetes
VS
lego
Let's Encrypt and ACME client written in Go
| Feature | cert-manager | lego |
|---|---|---|
| Deploy effort | Read-the-docs project | Under-an-hour setup |
| Health score | 94 · Excellent | 93 · Excellent |
| Category | Reverse Proxy & Gateways | Reverse Proxy & Gateways |
| License | Apache-2.0 | MIT |
| Language | Go | Go |
| Setup difficulty | Medium | Easy |
| Min. RAM | 256 MB | 64 MB |
| Deployment | kubernetes, helm | binary, docker |
| GitHub stars | ★ 14,088 | ★ 9,886 |
| First released | 2017 | 2015 |
| Replaces | Certbot | Certbot |
What are cert-manager and lego?
cert-manager
cert-manager is an open-source CNCF project that automates the issuance and renewal of TLS certificates in Kubernetes. It integrates with Let's Encrypt and other issuers for self-hosted clusters.
- Automatic certificate renewal
- ACME and CA issuers
- Kubernetes native
- DNS and HTTP challenges
lego
lego is an open-source ACME client and library for obtaining TLS certificates from Let's Encrypt and other ACME providers. It supports many DNS providers and is self-hosted for certificate automation.
- ACME certificate client
- 150+ DNS providers
- Single binary
- Usable as a library
cert-manager vs lego: key differences
Both projects are written in Go. Licensing differs — Apache-2.0 for cert-manager versus MIT for lego. Lego is the lighter option, starting around 64 MB of RAM against 256 MB for cert-manager. Lego is the more established project (first released 2015), while cert-manager arrived in 2017. Lego lists first-class Docker deployment; cert-manager does not.
Why pick each one
Choose cert-manager if…
- Hands-off certificate renewal
- CNCF graduated project
- Many issuer integrations
Watch out for
- Kubernetes only
- Debugging issuance can be tricky
Choose lego if…
- Released under the MIT license
- Easy to set up — beginner-friendly
- First-class Docker support for quick deployment
- Mature project with 9.9k GitHub stars
Frequently asked questions
Is cert-manager or lego better?
Neither is universally better. cert-manager has the larger community, while lego is simpler to set up (easy difficulty). Choose based on the comparison table above and your own setup.
Are cert-manager and lego free and open-source?
Yes. cert-manager is licensed under Apache-2.0 and lego under MIT. Both can be self-hosted at no software cost.
Can I run cert-manager and lego with Docker?
cert-manager: check the project docs for container support. lego: yes.
Which is lighter on resources, cert-manager or lego?
lego has the smaller minimum footprint at 64 MB of RAM, compared to about 256 MB for cert-manager. Real-world usage depends on library size, user count, and enabled features.