heimdall

heimdall is a Go-based library/CLI framework for implementing request signing and verification (in the style of an HMAC/secret-based guard) to authenticate clients and protect endpoints. It focuses on generating and validating signed requests/tokens to ensure integrity and authenticity.

Evaluated Mar 30, 2026 (30d ago)
Homepage ↗ Repo ↗ Security security authentication request-signing hmac go
⚙ Agent Friendliness
32
/ 100
Can an agent use this?
🔒 Security
56
/ 100
Is it safe for agents?
⚡ Reliability
30
/ 100
Does it work consistently?

Score Breakdown

⚙ Agent Friendliness

MCP Quality
0
Documentation
35
Error Messages
0
Auth Simplicity
60
Rate Limits
0

🔒 Security

TLS Enforcement
100
Auth Strength
70
Scope Granularity
20
Dep. Hygiene
45
Secret Handling
40

Strength depends on correct HMAC/signature implementation, secret storage, and replay protection (e.g., timestamps/nonces). Because it relies on shared secrets, compromise of the secret enables impersonation. Proper TLS and secret management are critical; the library's security is only as strong as its integration (canonicalization, expiry, and replay defenses).

⚡ Reliability

Uptime/SLA
0
Version Stability
50
Breaking Changes
50
Error Recovery
20
AF Security Reliability

Best When

You need lightweight request authentication using a shared secret and want deterministic verification of signed payloads/requests.

Avoid When

You need fine-grained user permissions, key rotation with standards-based identity, or you cannot safely manage shared secrets.

Use Cases

  • Protecting APIs with signed requests (HMAC-style) to prevent tampering
  • Verifying that inbound requests originate from trusted clients
  • Serving as a middleware/component for web services
  • Building lightweight API authentication without full OAuth flows

Not For

  • Authorization/identity management (users/roles) beyond possession of shared secrets
  • Zero-trust environments that require strong, standards-based identity (e.g., OAuth/OIDC) for end-user identity
  • Use cases requiring OAuth-based delegated authorization
  • High-level enterprise compliance reporting without additional surrounding controls

Interface

REST API
No
GraphQL
No
gRPC
No
MCP Server
No
SDK
Yes
Webhooks
No

Authentication

Methods: Shared-secret request signing (e.g., HMAC-style) for verification
OAuth: No Scopes: No

Authentication is based on possession of shared signing secrets and correct signature validation rather than OAuth/OIDC scopes.

Pricing

Free tier: No
Requires CC: No

As a library/tool, pricing is not applicable in the same way as hosted APIs.

Agent Metadata

Pagination
none
Idempotent
False
Retry Guidance
Not documented

Known Gotchas

  • As a library, agent integration depends on correct signing/verification wiring in the host application (middleware, canonicalization rules, clock skew/expiry handling).
  • If the library requires exact payload canonicalization, mismatches can lead to verification failures that look like auth errors.
  • Shared-secret management and rotation are the responsibility of the integrating service.

Alternatives

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Scores are editorial opinions as of 2026-03-30.

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