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MetalBear

July 21, 2026 2 min read
atprotopdscself-hosting

MetalBear is an AT Protocol Personal Data Server written in C and built on wolfram. It provides a runnable PDS foundation with multi-account hosting, admin tooling, and a dynamic landing page.

Version: 0.2.0

Core Features

  • com.atproto.server.describeServer, createSession, getSession, refreshSession, deleteSession
  • restart-persistent, HS256-signed AT Protocol access/refresh JWTs with refresh rotation
  • durable standard and privileged app passwords with one-time password display
  • repository-key-signed com.atproto.server.getServiceAuth JWT issuance
  • authenticated record creation, update, deletion, batch writes, and CAR import
  • public record reads, collection listing, repo description, and latest commit
  • full or revision-filtered CAR repository export and CID-selected block export
  • durable com.atproto.sync.subscribeRepos sequencing with live commit events
  • com.atproto.identity.resolveHandle, /.well-known/atproto-did, and did:web service document
  • com.atproto.identity.updateHandle and getRecommendedDidCredentials
  • durable account deactivation/reactivation
  • com.atproto.server.checkAccountStatus
  • com.atproto.server.reserveSigningKey
  • com.atproto.server.createInviteCode and createInviteCodes
  • durable SQLite-backed signed repositories and file-backed blob upload/serving

Admin Endpoints

  • com.atproto.admin.getAccountInfo — resolve DID to handle/email/active state
  • com.atproto.admin.sendEmail — send templated email
  • com.atproto.admin.getInviteCodes — list invite codes
  • com.atproto.admin.deleteAccount — permanently remove an account
  • com.atproto.admin.updateSubjectStatus — apply takedown, deactivation, or reactivation
  • com.atproto.admin.updateAccountPassword — reset account password
  • com.atproto.admin.enableAccountInvites / disableAccountInvites

OAuth Authorization Server

  • GET /.well-known/oauth-authorization-server — RFC 8414 server metadata
  • GET /.well-known/oauth-protected-resource — RFC 9728 resource metadata
  • GET /oauth/jwks — ES256 public JWK Set
  • POST /oauth/par — Pushed Authorization Request
  • GET /oauth/authorize — Authorization endpoint with auto-approval
  • POST /oauth/token — Token endpoint
  • POST /oauth/revoke — Token revocation

Build and Test

cmake -S . -B build
cmake --build build
ctest --test-dir build --output-on-failure

Run

export METALBEAR_SERVICE_DID='did:web:pds.example.com'
export METALBEAR_ACCOUNT_DID='did:plc:replace-with-your-account-did'
export METALBEAR_HANDLE='alice.example.com'
export METALBEAR_USER_DOMAIN='.example.com'
export METALBEAR_PASSWORD='replace-with-a-strong-password'
./build/metalbear

Email Configuration (Optional)

export METALBEAR_SMTP_HOST='smtp.example.com'
export METALBEAR_SMTP_PORT=587
export METALBEAR_SMTP_USERNAME='user@example.com'
export METALBEAR_SMTP_PASSWORD='your-smtp-password'
export METALBEAR_FROM_ADDRESS='pds@example.com'
export METALBEAR_FROM_NAME='My PDS'
export METALBEAR_ACCOUNT_EMAIL='alice@example.com'

Status

This is not yet a production-complete PDS. PLC DID document publication, TLS termination, and operational hardening remain to be implemented.

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