Mutual TLS Authentication (mTLS)
Definition
In mTLS, both sides of a connection prove their identity.
A TLS connection where server and client mutually authenticate each other based on trusted verified certificates.
Simply explained
Not only the door checks your ID: you also check the door’s ID.
Why it matters in practice
Helps develop and operate digital systems robustly, securely, and maintainably.
Example from business
Two internal services accept only certificates from the company CA.
Limits and pitfalls
- Treat mTLS as full authorization or neglect certificate rotation and revocation.
Origin & history
mTLS builds on TLS and the X.509 public key infrastructure.
Use in mid-sized companies
- Possible application: Two internal services accept only certificates from the company CA.
Frequently asked questions
What does Mutual TLS Authentication (mTLS) mean?
A TLS connection where server and client mutually authenticate each other based on trusted verified certificates.
Which mistakes should be avoided?
Treat mTLS as full authorization or neglect certificate rotation and revocation.
Sources
Source checked on 10.10.2026. Editorial application examples are hypothetical; no proof of real customer results.
Editorially reviewed on: