API keys or M2M applications: what should SaaS teams choose?

TL;DR: API keys are long-lived opaque secrets, while M2M applications issue short-lived JWTs through OAuth 2.0 client credentials, according to WorkOS. The real decision is not format but governance: how much lifecycle control, validation, and credential exposure risk your machine identity model can tolerate.

NHIMG editorial — based on content published by WorkOS: API Keys vs M2M Applications, differences, use cases, and how to decide

Questions worth separating out

Q: How should security teams govern API keys and M2M applications differently?

A: Security teams should govern API keys as standing bearer secrets and M2M applications as token minting systems with a separate long-lived secret.

Q: When does M2M create better machine identity control than API keys?

A: M2M is the better fit when the environment can support OAuth client credentials, short-lived tokens, and consistent JWT validation.

Q: What do teams get wrong about short-lived machine credentials?

A: Teams often assume that short-lived tokens eliminate machine identity risk.

Practitioner guidance

• Classify machine credentials by lifecycle, not by convenience Separate standing API keys from short-lived M2M tokens in policy, inventory, and review cycles so each credential type gets the control model it needs.
• Tie API key issuance to explicit revocation ownership Require a named owner for every organisation-scoped key, and make revocation part of the same workflow that approves creation and permission changes.
• Validate M2M tokens with a single trusted pattern Standardise JWKS caching or token introspection across services so JWT validation is consistent and does not depend on ad hoc implementation choices.

What's in the full article

WorkOS's full article covers the implementation detail this post intentionally leaves for the source:

• Step-by-step validation flow for API keys in request headers and backend checks
• OAuth client credentials sequence for M2M applications, including token issuance and JWKS validation
• Practical decision table for when to prefer simple opaque secrets versus short-lived JWTs
• Developer experience trade-offs that matter when your customers need self-service credential management

👉 Read WorkOS's comparison of API keys and M2M applications →

API keys or M2M applications: what should SaaS teams choose?

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