diff --git a/backend/openapi/components/schemas/claim.yaml b/backend/openapi/components/schemas/claim.yaml
new file mode 100644
index 0000000..87a7ac7
--- /dev/null
+++ b/backend/openapi/components/schemas/claim.yaml
@@ -0,0 +1,24 @@
+QuoteResult:
+  type: object
+  properties:
+    quote_id:
+      type: string
+    payout_sats:
+      type: integer
+    expires_at:
+      type: integer
+ConfirmResult:
+  type: object
+  properties:
+    success:
+      type: boolean
+    already_consumed:
+      type: boolean
+    payout_sats:
+      type: integer
+    next_eligible_at:
+      type: integer
+    message:
+      type: string
+    payment_hash:
+      type: string
diff --git a/backend/openapi/components/schemas/common.yaml b/backend/openapi/components/schemas/common.yaml
new file mode 100644
index 0000000..cb24e85
--- /dev/null
+++ b/backend/openapi/components/schemas/common.yaml
@@ -0,0 +1,12 @@
+ApiError:
+  type: object
+  required: [code, message]
+  properties:
+    code:
+      type: string
+    message:
+      type: string
+    details:
+      type: string
+    next_eligible_at:
+      type: integer
diff --git a/backend/openapi/components/schemas/faucet.yaml b/backend/openapi/components/schemas/faucet.yaml
new file mode 100644
index 0000000..5fd63c8
--- /dev/null
+++ b/backend/openapi/components/schemas/faucet.yaml
@@ -0,0 +1,64 @@
+FaucetConfig:
+  type: object
+  properties:
+    faucetEnabled:
+      type: boolean
+    emergencyStop:
+      type: boolean
+    cooldownDays:
+      type: integer
+    minAccountAgeDays:
+      type: integer
+    minActivityScore:
+      type: integer
+    faucetMinSats:
+      type: integer
+    faucetMaxSats:
+      type: integer
+Stats:
+  type: object
+  properties:
+    balanceSats:
+      type: integer
+    totalPaidSats:
+      type: integer
+    totalClaims:
+      type: integer
+    claimsLast24h:
+      type: integer
+    dailyBudgetSats:
+      type: integer
+    spentTodaySats:
+      type: integer
+    recentPayouts:
+      type: array
+      items:
+        type: object
+        properties:
+          pubkey_prefix:
+            type: string
+          payout_sats:
+            type: integer
+          claimed_at:
+            type: integer
+    recentDeposits:
+      type: array
+      items:
+        type: object
+        properties:
+          amount_sats:
+            type: integer
+          source:
+            type: string
+            enum: [lightning, cashu]
+          created_at:
+            type: integer
+DepositInfo:
+  type: object
+  properties:
+    lightningAddress:
+      type: string
+      nullable: true
+    lnurlp:
+      type: string
+      nullable: true
diff --git a/backend/openapi/components/schemas/user.yaml b/backend/openapi/components/schemas/user.yaml
new file mode 100644
index 0000000..3744e63
--- /dev/null
+++ b/backend/openapi/components/schemas/user.yaml
@@ -0,0 +1,9 @@
+UserProfile:
+  type: object
+  properties:
+    lightning_address:
+      type: string
+      nullable: true
+    name:
+      type: string
+      nullable: true
diff --git a/backend/openapi/components/security.yaml b/backend/openapi/components/security.yaml
new file mode 100644
index 0000000..c8d48d0
--- /dev/null
+++ b/backend/openapi/components/security.yaml
@@ -0,0 +1,9 @@
+NIP98:
+  type: http
+  scheme: bearer
+  bearerFormat: Nostr
+  description: NIP-98 HTTP Auth (Authorization Nostr <base64(json)>)
+BearerAuth:
+  type: http
+  scheme: bearer
+  bearerFormat: JWT
diff --git a/backend/openapi/index.yaml b/backend/openapi/index.yaml
new file mode 100644
index 0000000..20546ec
--- /dev/null
+++ b/backend/openapi/index.yaml
@@ -0,0 +1,60 @@
+openapi: 3.0.3
+info:
+  title: LNFaucet API
+  description: |
+    Lightning Network faucet: request small amounts of sats for testing.
+    Auth via NIP-98 (Nostr) or npub-only (limited).
+  version: 1.0.0
+servers:
+  - url: http://localhost:3001
+    description: Local development
+tags:
+  - name: Public
+    description: No authentication required
+  - name: Auth
+    description: NIP-98 or npub login
+  - name: Claim
+    description: Request sats (rate limited)
+  - name: User
+    description: Profile and refresh
+paths:
+  /health:
+    $ref: './path-items/health.yaml'
+  /config:
+    $ref: './path-items/config.yaml'
+  /stats:
+    $ref: './path-items/stats.yaml'
+  /deposit:
+    $ref: './path-items/deposit.yaml'
+  /deposit/redeem-cashu:
+    $ref: './path-items/deposit-redeem-cashu.yaml'
+  /auth/login:
+    $ref: './path-items/auth-login.yaml'
+  /auth/login-npub:
+    $ref: './path-items/auth-login-npub.yaml'
+  /auth/me:
+    $ref: './path-items/auth-me.yaml'
+  /claim/quote:
+    $ref: './path-items/claim-quote.yaml'
+  /claim/confirm:
+    $ref: './path-items/claim-confirm.yaml'
+  /user/refresh-profile:
+    $ref: './path-items/user-refresh-profile.yaml'
+components:
+  securitySchemes:
+    $ref: './components/security.yaml'
+  schemas:
+    FaucetConfig:
+      $ref: './components/schemas/faucet.yaml#/FaucetConfig'
+    Stats:
+      $ref: './components/schemas/faucet.yaml#/Stats'
+    DepositInfo:
+      $ref: './components/schemas/faucet.yaml#/DepositInfo'
+    QuoteResult:
+      $ref: './components/schemas/claim.yaml#/QuoteResult'
+    ConfirmResult:
+      $ref: './components/schemas/claim.yaml#/ConfirmResult'
+    UserProfile:
+      $ref: './components/schemas/user.yaml#/UserProfile'
+    ApiError:
+      $ref: './components/schemas/common.yaml#/ApiError'
diff --git a/backend/openapi/path-items/auth-login-npub.yaml b/backend/openapi/path-items/auth-login-npub.yaml
new file mode 100644
index 0000000..b296065
--- /dev/null
+++ b/backend/openapi/path-items/auth-login-npub.yaml
@@ -0,0 +1,33 @@
+post:
+  tags: [Auth]
+  summary: Sign in with npub only (limited)
+  requestBody:
+    content:
+      application/json:
+        schema:
+          type: object
+          required: [npub]
+          properties:
+            npub:
+              type: string
+  responses:
+    "200":
+      description: Token and pubkey
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              token:
+                type: string
+              pubkey:
+                type: string
+              method:
+                type: string
+                example: npub
+    "400":
+      description: Invalid npub
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
diff --git a/backend/openapi/path-items/auth-login.yaml b/backend/openapi/path-items/auth-login.yaml
new file mode 100644
index 0000000..20cfd3f
--- /dev/null
+++ b/backend/openapi/path-items/auth-login.yaml
@@ -0,0 +1,20 @@
+post:
+  tags: [Auth]
+  summary: Sign in with NIP-98 (returns JWT)
+  security:
+    - NIP98: []
+  responses:
+    "200":
+      description: Token and pubkey
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              token:
+                type: string
+              pubkey:
+                type: string
+              method:
+                type: string
+                example: nip98
diff --git a/backend/openapi/path-items/auth-me.yaml b/backend/openapi/path-items/auth-me.yaml
new file mode 100644
index 0000000..95ab47c
--- /dev/null
+++ b/backend/openapi/path-items/auth-me.yaml
@@ -0,0 +1,23 @@
+get:
+  tags: [Auth]
+  summary: Current user from Bearer token
+  security:
+    - BearerAuth: []
+  responses:
+    "200":
+      description: Pubkey and method
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              pubkey:
+                type: string
+              method:
+                type: string
+    "401":
+      description: Unauthorized or invalid token
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
diff --git a/backend/openapi/path-items/claim-confirm.yaml b/backend/openapi/path-items/claim-confirm.yaml
new file mode 100644
index 0000000..e709562
--- /dev/null
+++ b/backend/openapi/path-items/claim-confirm.yaml
@@ -0,0 +1,39 @@
+post:
+  tags: [Claim]
+  summary: Confirm quote and pay (rate limited)
+  security:
+    - BearerAuth: []
+  requestBody:
+    content:
+      application/json:
+        schema:
+          type: object
+          required: [quote_id]
+          properties:
+            quote_id:
+              type: string
+  responses:
+    "200":
+      description: Success or already consumed
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/claim.yaml#/ConfirmResult"
+    "400":
+      description: Invalid request
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
+    "404":
+      description: Quote not found or expired
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
+    "502":
+      description: Lightning payment failed
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
diff --git a/backend/openapi/path-items/claim-quote.yaml b/backend/openapi/path-items/claim-quote.yaml
new file mode 100644
index 0000000..d3cab55
--- /dev/null
+++ b/backend/openapi/path-items/claim-quote.yaml
@@ -0,0 +1,28 @@
+post:
+  tags: [Claim]
+  summary: Create claim quote (rate limited)
+  security:
+    - BearerAuth: []
+  requestBody:
+    content:
+      application/json:
+        schema:
+          type: object
+          required: [lightning_address]
+          properties:
+            lightning_address:
+              type: string
+              description: user@domain.tld
+  responses:
+    "200":
+      description: Quote
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/claim.yaml#/QuoteResult"
+    "403":
+      description: Not eligible or budget exceeded
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
diff --git a/backend/openapi/path-items/config.yaml b/backend/openapi/path-items/config.yaml
new file mode 100644
index 0000000..1110baa
--- /dev/null
+++ b/backend/openapi/path-items/config.yaml
@@ -0,0 +1,10 @@
+get:
+  tags: [Public]
+  summary: Public faucet config
+  responses:
+    "200":
+      description: Faucet configuration
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/faucet.yaml#/FaucetConfig"
diff --git a/backend/openapi/path-items/deposit-redeem-cashu.yaml b/backend/openapi/path-items/deposit-redeem-cashu.yaml
new file mode 100644
index 0000000..b80853c
--- /dev/null
+++ b/backend/openapi/path-items/deposit-redeem-cashu.yaml
@@ -0,0 +1,48 @@
+post:
+  tags: [Public]
+  summary: Redeem Cashu token
+  requestBody:
+    required: true
+    content:
+      application/json:
+        schema:
+          type: object
+          required: [token]
+          properties:
+            token:
+              type: string
+              description: Cashu token (cashuA... or cashuB...)
+  responses:
+    "200":
+      description: Redeem result
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              success:
+                type: boolean
+              paid:
+                type: boolean
+              amount:
+                type: integer
+              invoiceAmount:
+                type: integer
+              netAmount:
+                type: integer
+              to:
+                type: string
+              message:
+                type: string
+    "400":
+      description: Invalid token or address
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
+    "502":
+      description: Redeem failed
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
diff --git a/backend/openapi/path-items/deposit.yaml b/backend/openapi/path-items/deposit.yaml
new file mode 100644
index 0000000..383034e
--- /dev/null
+++ b/backend/openapi/path-items/deposit.yaml
@@ -0,0 +1,10 @@
+get:
+  tags: [Public]
+  summary: Deposit info
+  responses:
+    "200":
+      description: Lightning address and LNURLp
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/faucet.yaml#/DepositInfo"
diff --git a/backend/openapi/path-items/health.yaml b/backend/openapi/path-items/health.yaml
new file mode 100644
index 0000000..fa98f6f
--- /dev/null
+++ b/backend/openapi/path-items/health.yaml
@@ -0,0 +1,14 @@
+get:
+  tags: [Public]
+  summary: Health check
+  responses:
+    "200":
+      description: OK
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              status:
+                type: string
+                example: ok
diff --git a/backend/openapi/path-items/stats.yaml b/backend/openapi/path-items/stats.yaml
new file mode 100644
index 0000000..76b6064
--- /dev/null
+++ b/backend/openapi/path-items/stats.yaml
@@ -0,0 +1,16 @@
+get:
+  tags: [Public]
+  summary: Faucet stats
+  responses:
+    "200":
+      description: Stats (balance, paid, claims)
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/faucet.yaml#/Stats"
+    "500":
+      description: Internal error
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
diff --git a/backend/openapi/path-items/user-refresh-profile.yaml b/backend/openapi/path-items/user-refresh-profile.yaml
new file mode 100644
index 0000000..a965434
--- /dev/null
+++ b/backend/openapi/path-items/user-refresh-profile.yaml
@@ -0,0 +1,18 @@
+post:
+  tags: [User]
+  summary: Refresh Nostr profile (kind 0)
+  security:
+    - BearerAuth: []
+  responses:
+    "200":
+      description: lightning_address and name
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/user.yaml#/UserProfile"
+    "500":
+      description: Profile fetch failed
+      content:
+        application/json:
+          schema:
+            $ref: "../components/schemas/common.yaml#/ApiError"
diff --git a/backend/package-lock.json b/backend/package-lock.json
index b72e3b8..d231179 100644
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
@@ -8,6 +8,7 @@
       "name": "lnfaucet-backend",
       "version": "1.0.0",
       "dependencies": {
+        "@apidevtools/swagger-parser": "^12.1.0",
         "better-sqlite3": "^11.6.0",
         "cors": "^2.8.5",
         "dotenv": "^16.4.5",
@@ -15,6 +16,7 @@
         "express-rate-limit": "^7.4.1",
         "nostr-tools": "^2.4.4",
         "pg": "^8.13.1",
+        "swagger-ui-express": "^5.0.1",
         "uuid": "^10.0.0"
       },
       "devDependencies": {
@@ -23,11 +25,60 @@
         "@types/express": "^4.17.21",
         "@types/node": "^22.9.0",
         "@types/pg": "^8.11.10",
+        "@types/swagger-ui-express": "^4.1.8",
         "@types/uuid": "^10.0.0",
         "tsx": "^4.19.2",
         "typescript": "^5.6.3"
       }
     },
+    "node_modules/@apidevtools/json-schema-ref-parser": {
+      "version": "14.0.1",
+      "resolved": "https://registry.npmjs.org/@apidevtools/json-schema-ref-parser/-/json-schema-ref-parser-14.0.1.tgz",
+      "integrity": "sha512-Oc96zvmxx1fqoSEdUmfmvvb59/KDOnUoJ7s2t7bISyAn0XEz57LCCw8k2Y4Pf3mwKaZLMciESALORLgfe2frCw==",
+      "license": "MIT",
+      "dependencies": {
+        "@types/json-schema": "^7.0.15",
+        "js-yaml": "^4.1.0"
+      },
+      "engines": {
+        "node": ">= 16"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/philsturgeon"
+      }
+    },
+    "node_modules/@apidevtools/openapi-schemas": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/@apidevtools/openapi-schemas/-/openapi-schemas-2.1.0.tgz",
+      "integrity": "sha512-Zc1AlqrJlX3SlpupFGpiLi2EbteyP7fXmUOGup6/DnkRgjP9bgMM/ag+n91rsv0U1Gpz0H3VILA/o3bW7Ua6BQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=10"
+      }
+    },
+    "node_modules/@apidevtools/swagger-methods": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/@apidevtools/swagger-methods/-/swagger-methods-3.0.2.tgz",
+      "integrity": "sha512-QAkD5kK2b1WfjDS/UQn/qQkbwF31uqRjPTrsCs5ZG9BQGAkjwvqGFjjPqAuzac/IYzpPtRzjCP1WrTuAIjMrXg==",
+      "license": "MIT"
+    },
+    "node_modules/@apidevtools/swagger-parser": {
+      "version": "12.1.0",
+      "resolved": "https://registry.npmjs.org/@apidevtools/swagger-parser/-/swagger-parser-12.1.0.tgz",
+      "integrity": "sha512-e5mJoswsnAX0jG+J09xHFYQXb/bUc5S3pLpMxUuRUA2H8T2kni3yEoyz2R3Dltw5f4A6j6rPNMpWTK+iVDFlng==",
+      "license": "MIT",
+      "dependencies": {
+        "@apidevtools/json-schema-ref-parser": "14.0.1",
+        "@apidevtools/openapi-schemas": "^2.1.0",
+        "@apidevtools/swagger-methods": "^3.0.2",
+        "ajv": "^8.17.1",
+        "ajv-draft-04": "^1.0.0",
+        "call-me-maybe": "^1.0.2"
+      },
+      "peerDependencies": {
+        "openapi-types": ">=7"
+      }
+    },
     "node_modules/@esbuild/aix-ppc64": {
       "version": "0.27.3",
       "resolved": "https://registry.npmjs.org/@esbuild/aix-ppc64/-/aix-ppc64-0.27.3.tgz",
@@ -509,6 +560,13 @@
         "url": "https://paulmillr.com/funding/"
       }
     },
+    "node_modules/@scarf/scarf": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/@scarf/scarf/-/scarf-1.4.0.tgz",
+      "integrity": "sha512-xxeapPiUXdZAE3che6f3xogoJPeZgig6omHEy1rIY5WVsB3H2BHNnZH+gHG6x91SCWyQCzWGsuL2Hh3ClO5/qQ==",
+      "hasInstallScript": true,
+      "license": "Apache-2.0"
+    },
     "node_modules/@scure/base": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/@scure/base/-/base-2.0.0.tgz",
@@ -619,6 +677,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/json-schema": {
+      "version": "7.0.15",
+      "resolved": "https://registry.npmjs.org/@types/json-schema/-/json-schema-7.0.15.tgz",
+      "integrity": "sha512-5+fP8P8MFNC+AyZCDxrB2pkZFPGzqQWUzpSeuuVLvm8VMcorNYavBqoFcxK8bQz4Qsbn4oUEEem4wDLfcysGHA==",
+      "license": "MIT"
+    },
     "node_modules/@types/mime": {
       "version": "1.3.5",
       "resolved": "https://registry.npmjs.org/@types/mime/-/mime-1.3.5.tgz",
@@ -695,6 +759,17 @@
         "@types/node": "*"
       }
     },
+    "node_modules/@types/swagger-ui-express": {
+      "version": "4.1.8",
+      "resolved": "https://registry.npmjs.org/@types/swagger-ui-express/-/swagger-ui-express-4.1.8.tgz",
+      "integrity": "sha512-AhZV8/EIreHFmBV5wAs0gzJUNq9JbbSXgJLQubCC0jtIo6prnI9MIRRxnU4MZX9RB9yXxF1V4R7jtLl/Wcj31g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/express": "*",
+        "@types/serve-static": "*"
+      }
+    },
     "node_modules/@types/uuid": {
       "version": "10.0.0",
       "resolved": "https://registry.npmjs.org/@types/uuid/-/uuid-10.0.0.tgz",
@@ -715,6 +790,42 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/ajv": {
+      "version": "8.18.0",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.18.0.tgz",
+      "integrity": "sha512-PlXPeEWMXMZ7sPYOHqmDyCJzcfNrUr3fGNKtezX14ykXOEIvyK81d+qydx89KY5O71FKMPaQ2vBfBFI5NHR63A==",
+      "license": "MIT",
+      "dependencies": {
+        "fast-deep-equal": "^3.1.3",
+        "fast-uri": "^3.0.1",
+        "json-schema-traverse": "^1.0.0",
+        "require-from-string": "^2.0.2"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/epoberezkin"
+      }
+    },
+    "node_modules/ajv-draft-04": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/ajv-draft-04/-/ajv-draft-04-1.0.0.tgz",
+      "integrity": "sha512-mv00Te6nmYbRp5DCwclxtt7yV/joXJPGS7nM+97GdxvuttCOfgI3K4U25zboyeX0O+myI8ERluxQe5wljMmVIw==",
+      "license": "MIT",
+      "peerDependencies": {
+        "ajv": "^8.5.0"
+      },
+      "peerDependenciesMeta": {
+        "ajv": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/argparse": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/argparse/-/argparse-2.0.1.tgz",
+      "integrity": "sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==",
+      "license": "Python-2.0"
+    },
     "node_modules/array-flatten": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/array-flatten/-/array-flatten-1.1.1.tgz",
@@ -858,6 +969,12 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/call-me-maybe": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/call-me-maybe/-/call-me-maybe-1.0.2.tgz",
+      "integrity": "sha512-HpX65o1Hnr9HH25ojC1YGs7HCQLq0GCOibSaWER0eNpgJ/Z1MZv2mTc7+xh6WOPxbRVcmgbv4hGU+uSQ/2xFZQ==",
+      "license": "MIT"
+    },
     "node_modules/chownr": {
       "version": "1.1.4",
       "resolved": "https://registry.npmjs.org/chownr/-/chownr-1.1.4.tgz",
@@ -1185,6 +1302,28 @@
         "express": ">= 4.11"
       }
     },
+    "node_modules/fast-deep-equal": {
+      "version": "3.1.3",
+      "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
+      "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==",
+      "license": "MIT"
+    },
+    "node_modules/fast-uri": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.0.tgz",
+      "integrity": "sha512-iPeeDKJSWf4IEOasVVrknXpaBV0IApz/gp7S2bb7Z4Lljbl2MGJRqInZiUrQwV16cpzw/D3S5j5Julj/gT52AA==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
+      "license": "BSD-3-Clause"
+    },
     "node_modules/file-uri-to-path": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/file-uri-to-path/-/file-uri-to-path-1.0.0.tgz",
@@ -1422,6 +1561,24 @@
         "node": ">= 0.10"
       }
     },
+    "node_modules/js-yaml": {
+      "version": "4.1.1",
+      "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-4.1.1.tgz",
+      "integrity": "sha512-qQKT4zQxXl8lLwBtHMWwaTcGfFOZviOJet3Oy/xmGk2gZH677CJM9EvtfdSkgWcATZhj/55JZ0rmy3myCT5lsA==",
+      "license": "MIT",
+      "dependencies": {
+        "argparse": "^2.0.1"
+      },
+      "bin": {
+        "js-yaml": "bin/js-yaml.js"
+      }
+    },
+    "node_modules/json-schema-traverse": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/json-schema-traverse/-/json-schema-traverse-1.0.0.tgz",
+      "integrity": "sha512-NM8/P9n3XjXhIZn1lLhkFaACTOURQXjWhV4BA/RnOv8xvgqtqpAX9IO4mRQxSx1Rlo4tqzeqb0sOlruaOy3dug==",
+      "license": "MIT"
+    },
     "node_modules/math-intrinsics": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/math-intrinsics/-/math-intrinsics-1.1.0.tgz",
@@ -1622,6 +1779,13 @@
         "wrappy": "1"
       }
     },
+    "node_modules/openapi-types": {
+      "version": "12.1.3",
+      "resolved": "https://registry.npmjs.org/openapi-types/-/openapi-types-12.1.3.tgz",
+      "integrity": "sha512-N4YtSYJqghVu4iek2ZUvcN/0aqH1kRDuNqzcycDxhOUpg7GdvLa2F3DgS6yBNhInhv2r/6I0Flkn7CqL8+nIcw==",
+      "license": "MIT",
+      "peer": true
+    },
     "node_modules/parseurl": {
       "version": "1.3.3",
       "resolved": "https://registry.npmjs.org/parseurl/-/parseurl-1.3.3.tgz",
@@ -1883,6 +2047,15 @@
         "node": ">= 6"
       }
     },
+    "node_modules/require-from-string": {
+      "version": "2.0.2",
+      "resolved": "https://registry.npmjs.org/require-from-string/-/require-from-string-2.0.2.tgz",
+      "integrity": "sha512-Xf0nWe6RseziFMu+Ap9biiUbmplq6S9/p+7w7YXP/JBHhrUDDUhwa+vANyubuqfZWTveU//DYVGsDG7RKL/vEw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
     "node_modules/resolve-pkg-maps": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/resolve-pkg-maps/-/resolve-pkg-maps-1.0.0.tgz",
@@ -2135,6 +2308,30 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/swagger-ui-dist": {
+      "version": "5.32.0",
+      "resolved": "https://registry.npmjs.org/swagger-ui-dist/-/swagger-ui-dist-5.32.0.tgz",
+      "integrity": "sha512-nKZB0OuDvacB0s/lC2gbge+RigYvGRGpLLMWMFxaTUwfM+CfndVk9Th2IaTinqXiz6Mn26GK2zriCpv6/+5m3Q==",
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@scarf/scarf": "=1.4.0"
+      }
+    },
+    "node_modules/swagger-ui-express": {
+      "version": "5.0.1",
+      "resolved": "https://registry.npmjs.org/swagger-ui-express/-/swagger-ui-express-5.0.1.tgz",
+      "integrity": "sha512-SrNU3RiBGTLLmFU8GIJdOdanJTl4TOmT27tt3bWWHppqYmAZ6IDuEuBvMU6nZq0zLEe6b/1rACXCgLZqO6ZfrA==",
+      "license": "MIT",
+      "dependencies": {
+        "swagger-ui-dist": ">=5.0.0"
+      },
+      "engines": {
+        "node": ">= v0.10.32"
+      },
+      "peerDependencies": {
+        "express": ">=4.0.0 || >=5.0.0-beta"
+      }
+    },
     "node_modules/tar-fs": {
       "version": "2.1.4",
       "resolved": "https://registry.npmjs.org/tar-fs/-/tar-fs-2.1.4.tgz",
diff --git a/backend/package.json b/backend/package.json
index 8722af2..cade6a5 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -10,6 +10,7 @@
     "migrate": "tsx src/db/migrate.ts"
   },
   "dependencies": {
+    "@apidevtools/swagger-parser": "^12.1.0",
     "better-sqlite3": "^11.6.0",
     "cors": "^2.8.5",
     "dotenv": "^16.4.5",
@@ -17,6 +18,7 @@
     "express-rate-limit": "^7.4.1",
     "nostr-tools": "^2.4.4",
     "pg": "^8.13.1",
+    "swagger-ui-express": "^5.0.1",
     "uuid": "^10.0.0"
   },
   "devDependencies": {
@@ -25,6 +27,7 @@
     "@types/express": "^4.17.21",
     "@types/node": "^22.9.0",
     "@types/pg": "^8.11.10",
+    "@types/swagger-ui-express": "^4.1.8",
     "@types/uuid": "^10.0.0",
     "tsx": "^4.19.2",
     "typescript": "^5.6.3"
diff --git a/backend/src/index.ts b/backend/src/index.ts
index d2f6e27..27f365c 100644
--- a/backend/src/index.ts
+++ b/backend/src/index.ts
@@ -8,6 +8,7 @@ import publicRoutes from "./routes/public.js";
 import authRoutes from "./routes/auth.js";
 import claimRoutes from "./routes/claim.js";
 import userRoutes from "./routes/user.js";
+import docsRoutes from "./routes/docs.js";
 
 const NONCE_CLEANUP_INTERVAL_MS = 5 * 60 * 1000; // 5 minutes
 
@@ -39,6 +40,7 @@ async function main() {
     })
   );
 
+  app.use("/", docsRoutes);
   app.use("/", publicRoutes);
   app.use("/auth", authRoutes);
   app.use(
diff --git a/backend/src/routes/docs.ts b/backend/src/routes/docs.ts
new file mode 100644
index 0000000..0becc20
--- /dev/null
+++ b/backend/src/routes/docs.ts
@@ -0,0 +1,40 @@
+import { Router, Request, Response } from "express";
+import path from "path";
+import { fileURLToPath } from "url";
+import SwaggerParser from "@apidevtools/swagger-parser";
+import swaggerUi from "swagger-ui-express";
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const openApiPath = path.join(__dirname, "..", "..", "openapi", "index.yaml");
+
+let cachedSpec: object | null = null;
+
+async function getBundledSpec(): Promise<object> {
+  if (cachedSpec) return cachedSpec;
+  cachedSpec = (await SwaggerParser.bundle(openApiPath)) as object;
+  return cachedSpec;
+}
+
+const router = Router();
+
+router.get("/openapi.json", async (_req: Request, res: Response) => {
+  try {
+    const spec = await getBundledSpec();
+    res.json(spec);
+  } catch (err) {
+    console.error("[docs] Failed to bundle OpenAPI spec:", err);
+    res.status(500).json({ code: "openapi_error", message: "Failed to load API spec" });
+  }
+});
+
+router.use(
+  "/docs",
+  swaggerUi.serve,
+  swaggerUi.setup(null, {
+    swaggerOptions: {
+      url: "/openapi.json",
+    },
+  })
+);
+
+export default router;