generated: '2026-08-12'
method: searched
source: https://docs.epsilon3.io/#authentication
docs: https://support.epsilon3.io/en/articles/8779712-generate-api-key
note: >-
  Derived mechanically from OpenAPI was not possible - Epsilon3 publishes no machine
  readable spec. This profile is transcribed from the published API Guide plus the
  RFC 8414 / RFC 9728 metadata documents actually served by the API and MCP hosts.
summary:
  types: [http, oauth2]
  http_schemes: [basic]
  api_key_in: [header]
  api_key_transport: HTTP Basic username component
  oauth2_flows: [authorizationCode]
  oauth2_surface: MCP server only
schemes:
- name: ApiKeyBasic
  type: http
  scheme: basic
  applies_to: Epsilon3 REST API (https://api.epsilon3.io/v1)
  description: >-
    A per-workspace API key is supplied as the USERNAME component of an HTTP Basic
    Authorization header with an empty password - curl -u "$EPSILON3_API_KEY": - which
    the docs demonstrate in curl, Python requests and PowerShell. There is no bearer
    token, no signed request and no separate secret.
  source: https://docs.epsilon3.io/#authentication
  key_scoping:
  - scope: team
    note: >-
      Team-scoped keys are the default and are REQUIRED for realtime (SocketIO/webhook)
      client authentication - the docs state user-scoped keys will not work there.
  - scope: user
    note: >-
      User-scoped API keys were added in Changelog #97 (2026-04-03) and are issued from
      User > Profile > API Keys. At least one documented endpoint requires a user key
      and returns 403 for a team key.
  key_generation: https://support.epsilon3.io/en/articles/8779712-generate-api-key
- name: RealtimeWebhookSignature
  type: signature
  applies_to: Epsilon3 Realtime API webhooks
  description: >-
    Inbound webhook deliveries carry an Epsilon3-Signature header. Epsilon3 ships a
    python module named webhook_auth exposing verify_webhook_signature(secret, payload,
    signature) which returns True/False. The signing algorithm is not published; the
    docs direct integrators to contact Epsilon3 support to verify signatures manually.
    A webhook key must be registered by Epsilon3 support - it is not self-service.
  header: Epsilon3-Signature
  secret_env: EPSILON3_WEBHOOK_KEY
  algorithm_published: false
  source: https://docs.epsilon3.io/#webhook-signature-verification
- name: MCPOAuth
  type: oauth2
  applies_to: Epsilon3 MCP Server (https://mcp.epsilon3.io)
  description: >-
    The hosted MCP server is protected by OAuth 2.1 authorization-code with PKCE.
    Public clients only - token_endpoint_auth_methods_supported is ["none"] - and
    dynamic client registration (RFC 7591) is open, which is what lets an MCP client
    self-register as a connector. An Epsilon3 API key may alternatively be presented
    as a bearer token.
  flows:
  - flow: authorizationCode
    authorizationUrl: https://app.epsilon3.io/oauth/authorize
    tokenUrl: https://app.epsilon3.io/oauth/token
    registrationUrl: https://app.epsilon3.io/oauth/register
    code_challenge_methods_supported: [S256]
    grant_types_supported: [authorization_code, refresh_token]
    response_types_supported: [code]
    token_endpoint_auth_methods_supported: [none]
    scope_count: 15
    scopes: scopes/epsilon3-scopes.yml
  sources:
  - well-known/epsilon3-mcp-oauth-authorization-server.json
  - well-known/epsilon3-mcp-oauth-protected-resource.json
- name: PlatformOAuth
  type: oauth2
  applies_to: api.epsilon3.io and api.uk.epsilon3.io
  description: >-
    The API hosts serve their own RFC 8414 authorization-server metadata with the same
    fifteen scopes, issuer-local endpoints, PKCE S256 and open dynamic client
    registration. This OAuth surface is NOT documented in the API Guide - the guide only
    describes API-key Basic auth - so it is recorded here from the served metadata, and
    an integrator should treat it as undocumented until Epsilon3 publishes it.
  flows:
  - flow: authorizationCode
    authorizationUrl: https://api.epsilon3.io/oauth/authorize
    tokenUrl: https://api.epsilon3.io/oauth/token
    registrationUrl: https://api.epsilon3.io/oauth/register
    code_challenge_methods_supported: [S256]
    scope_count: 15
  sources:
  - well-known/epsilon3-oauth-authorization-server.json
sso:
  available: true
  mechanisms: [SAML, SSO, MFA]
  tier: Pro and Enterprise plans
  source: https://www.epsilon3.io/security
gaps:
- No OpenID Connect discovery document is served on any host (/.well-known/openid-configuration
  404s on the docs/www hosts and returns the SPA shell on api/app).
- The webhook signature algorithm is not published, so signature verification cannot be
  implemented without contacting support - a real interoperability barrier for any
  non-Python consumer.
- The platform-level OAuth surface on api.epsilon3.io is served but undocumented.