Integration Options

Signer API Service

The Signer API Service is a Next.js API service that provides both standard signing and gasless signing endpoints for the Ethereum Comments Protocol. It allows you to sign comments and optionally submit them without user gas costs.

Features

Standard Signing: Sign comments with app signature
Gasless Signing: Submit comments without user gas costs
Approval Checking: Automatically submit comments if user has approved the app
Edit Comment Support: Sign and submit comment edits
Delete Comment Support: Sign and submit comment deletions
Multi-Chain Support: Configure multiple chains with individual RPC URLs
Conditional Endpoints: Gasless endpoint only available when properly configured
Type Safety: Full TypeScript support with Zod validation
Vercel Ready: Optimized for Vercel deployment

Quick Start

Deploy to Vercel

Manual Setup

Clone and install dependencies:

git clone https://github.com/ecp-eth/comments-monorepo.git
cd apps/signer
pnpm install

Set up environment variables:

cp .env.example .env.local
# Edit .env.local with your values

Run the development server:
```
pnpm dev
```

Environment Variables

Required

ENABLED_CHAINS: Comma-separated list of chain IDs supported by the endpoints (must be supported by @ecp.eth/sdk)
DEFAULT_CHAIN_ID: Default chain ID for the service (must be one of the enabled chains and supported by @ecp.eth/sdk)
RPC_URL_{chainId}: RPC URL for each enabled chain (e.g., RPC_URL_31337 for chain 31337)

Optional

APP_SIGNER_PRIVATE_KEY: Private key for app signer used to sign comments using /api/sign. If not set, the endpoint will return 404
COMMENTS_INDEXER_URL: Comments indexer URL for muted account checking. If not set, the check is disabled

Gasless Configuration

For gasless (sponsored) transactions, you can use either private key method or Privy method. If both are configured, the private key method will be used.

Method Selection

GASLESS_METHOD: Which method to use for preparing and sending comments
- "private-key": Uses GASLESS_APP_SIGNER_PRIVATE_KEY + GASLESS_SUBMITTER_PRIVATE_KEY
- "privy": Uses GASLESS_PRIVY_APP_SIGNER_PRIVATE_KEY + GASLESS_PRIVY_* variables
- If not set, gasless endpoints will return 404

Private Key Method (`"private-key"`)

GASLESS_APP_SIGNER_PRIVATE_KEY: Used to sign comment data using /api/gasless/prepare endpoint. If not set, GASLESS_SUBMITTER_PRIVATE_KEY will be used
GASLESS_SUBMITTER_PRIVATE_KEY: Required - Used to send signed comment data using /api/gasless/send endpoint

Privy Method (`"privy"`)

GASLESS_PRIVY_APP_SIGNER_PRIVATE_KEY: Used to sign comment data using /api/gasless/sign endpoint. If not set, the Privy account is used to sign
GASLESS_PRIVY_APP_ID: Required - Privy app ID
GASLESS_PRIVY_SECRET: Required - Privy secret
GASLESS_PRIVY_AUTHORIZATION_KEY: Required - Privy authorization key
GASLESS_PRIVY_WALLET_ADDRESS: Required - Privy wallet address
GASLESS_PRIVY_WALLET_ID: Required - Privy wallet ID

API Endpoints

POST /api/post-comment/sign

Standard comment signing endpoint. Always available when APP_SIGNER_PRIVATE_KEY is configured.

Request:

{
  "author": "0x1234567890abcdef1234567890abcdef1234567890",
  "content": "Your comment text",
  "metadata": [],
  "targetUri": "https://example.com"
}

Response:

{
  "signature": "0x...",
  "hash": "0x...",
  "data": {
    "id": "0x...",
    "content": "Your comment text",
    "author": "0x1234567890abcdef1234567890abcdef1234567890",
    "app": "0x...",
    "targetUri": "https://example.com",
    "metadata": [],
    "timestamp": "1234567890"
  }
}

POST /api/post-comment/gasless/prepare

Prepare gasless comment data. Returns 404 if gasless method is not configured.

Request:

{
  "author": "0x1234567890abcdef1234567890abcdef1234567890",
  "content": "Your comment text",
  "metadata": [],
  "targetUri": "https://example.com",
  "submitIfApproved": true
}

Response (Not Approved):

{
  "signTypedDataParams": { ... },
  "id": "0x...",
  "appSignature": "0x...",
  "commentData": { ... },
  "chainId": 1
}

Response (Approved and Submitted):

{
  "txHash": "0x...",
  "id": "0x...",
  "appSignature": "0x...",
  "commentData": { ... },
  "chainId": 1
}

POST /api/post-comment/gasless/send

Send signed gasless comment data. Returns 404 if gasless method is not configured.

Request:

{
  "signTypedDataParams": { ... },
  "appSignature": "0x...",
  "authorSignature": "0x...",
  "chainId": 1
}

Response:

{
  "txHash": "0x..."
}

Edit Comment Endpoints

POST /api/edit-comment/sign

Standard edit comment signing endpoint. Always available when APP_SIGNER_PRIVATE_KEY is configured.

Request:

{
  "commentId": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
  "content": "Updated comment text",
  "author": "0x1234567890abcdef1234567890abcdef1234567890",
  "metadata": [],
  "chainId": 1
}

Response:

{
  "signature": "0x...",
  "hash": "0x...",
  "data": {
    "commentId": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    "content": "Updated comment text",
    "app": "0x...",
    "nonce": "1234567890",
    "deadline": "1234567890",
    "metadata": []
  }
}

POST /api/edit-comment/gasless/prepare

Prepare gasless edit comment data. Returns 404 if gasless method is not configured.

Request:

{
  "commentId": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
  "content": "Updated comment text",
  "author": "0x1234567890abcdef1234567890abcdef1234567890",
  "metadata": [],
  "submitIfApproved": true,
  "chainId": 1
}

Response (Not Approved):

{
  "signTypedDataParams": { ... },
  "appSignature": "0x...",
  "chainId": 1,
  "edit": { ... }
}

Response (Approved and Submitted):

{
  "txHash": "0x...",
  "appSignature": "0x...",
  "chainId": 1,
  "edit": { ... }
}

POST /api/edit-comment/gasless/send

Send signed gasless edit comment data. Returns 404 if gasless method is not configured.

Request:

{
  "signTypedDataParams": { ... },
  "appSignature": "0x...",
  "authorSignature": "0x...",
  "edit": { ... },
  "chainId": 1
}

Response:

{
  "txHash": "0x..."
}

Delete Comment Endpoints

POST /api/delete-comment/gasless/prepare

Prepare gasless delete comment data. Returns 404 if gasless method is not configured.

Request:

{
  "author": "0x1234567890abcdef1234567890abcdef1234567890",
  "commentId": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
  "submitIfApproved": true,
  "chainId": 1
}

Response (Not Approved):

{
  "signTypedDataParams": { ... },
  "appSignature": "0x..."
}

Response (Approved and Submitted):

{
  "txHash": "0x..."
}

POST /api/delete-comment/gasless/send

Send signed gasless delete comment data. Returns 404 if gasless method is not configured.

Request:

{
  "signTypedDataParams": { ... },
  "appSignature": "0x...",
  "authorSignature": "0x...",
  "chainId": 1
}

Response:

{
  "txHash": "0x..."
}

Usage Examples

cURL - Standard Signing

curl -X POST http://localhost:3000/api/post-comment/sign \
  -H "Content-Type: application/json" \
  -d '{
    "author": "0x1234567890abcdef1234567890abcdef1234567890",
    "content": "Hello, world!",
    "metadata": [],
    "targetUri": "https://example.com"
  }'

cURL - Gasless Prepare

curl -X POST http://localhost:3000/api/post-comment/gasless/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "author": "0x1234567890abcdef1234567890abcdef1234567890",
    "content": "Hello, world!",
    "metadata": [],
    "targetUri": "https://example.com",
    "submitIfApproved": true
  }'

cURL - Gasless Send

curl -X POST http://localhost:3000/api/post-comment/gasless/send \
  -H "Content-Type: application/json" \
  -d '{
    "signTypedDataParams": { ... },
    "appSignature": "0x...",
    "authorSignature": "0x...",
    "chainId": 1
  }'

cURL - Edit Comment Sign

curl -X POST http://localhost:3000/api/edit-comment/sign \
  -H "Content-Type: application/json" \
  -d '{
    "commentId": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    "content": "Updated comment text",
    "author": "0x1234567890abcdef1234567890abcdef1234567890",
    "metadata": [],
    "chainId": 1
  }'

cURL - Edit Comment Gasless Prepare

curl -X POST http://localhost:3000/api/edit-comment/gasless/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "commentId": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    "content": "Updated comment text",
    "author": "0x1234567890abcdef1234567890abcdef1234567890",
    "metadata": [],
    "submitIfApproved": true,
    "chainId": 1
  }'

cURL - Edit Comment Gasless Send

curl -X POST http://localhost:3000/api/edit-comment/gasless/send \
  -H "Content-Type: application/json" \
  -d '{
    "signTypedDataParams": { ... },
    "appSignature": "0x...",
    "authorSignature": "0x...",
    "edit": { ... },
    "chainId": 1
  }'

cURL - Delete Comment Gasless Prepare

curl -X POST http://localhost:3000/api/delete-comment/gasless/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "author": "0x1234567890abcdef1234567890abcdef1234567890",
    "commentId": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    "submitIfApproved": true,
    "chainId": 1
  }'

cURL - Delete Comment Gasless Send

curl -X POST http://localhost:3000/api/delete-comment/gasless/send \
  -H "Content-Type: application/json" \
  -d '{
    "signTypedDataParams": { ... },
    "appSignature": "0x...",
    "authorSignature": "0x...",
    "chainId": 1
  }'

TypeScript

// Standard signing
const response = await fetch("/api/post-comment/sign", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    author: "0x1234567890abcdef1234567890abcdef1234567890",
    content: "Hello, world!",
    metadata: [],
    targetUri: "https://example.com",
  }),
});
 
const result = await response.json();
console.log(result.signature);
 
// Gasless flow with approval checking
const prepareResponse = await fetch("/api/post-comment/gasless/prepare", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    author: "0x1234567890abcdef1234567890abcdef1234567890",
    content: "Hello, world!",
    metadata: [],
    targetUri: "https://example.com",
    submitIfApproved: true, // Check if user has approved the app
  }),
});
 
const prepareResult = await prepareResponse.json();
 
// Check if comment was already submitted (user has approval)
if (prepareResult.txHash) {
  console.log("Comment submitted automatically:", prepareResult.txHash);
} else {
  // User needs to sign the data with their wallet
  const userSignature = await userWallet.signTypedData(
    prepareResult.signTypedDataParams,
  );
 
  // Send the signed data
  const sendResponse = await fetch("/api/post-comment/gasless/send", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      signTypedDataParams: prepareResult.signTypedDataParams,
      appSignature: prepareResult.appSignature,
      authorSignature: userSignature,
      chainId: 1,
    }),
  });
 
  const sendResult = await sendResponse.json();
  console.log(sendResult.txHash);
}
 
// Edit comment - Standard signing
const editResponse = await fetch("/api/edit-comment/sign", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    commentId:
      "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    content: "Updated comment text",
    author: "0x1234567890abcdef1234567890abcdef1234567890",
    metadata: [],
    chainId: 1,
  }),
});
 
const editResult = await editResponse.json();
console.log(editResult.signature);
 
// Edit comment - Gasless flow
const editPrepareResponse = await fetch("/api/edit-comment/gasless/prepare", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    commentId:
      "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    content: "Updated comment text",
    author: "0x1234567890abcdef1234567890abcdef1234567890",
    metadata: [],
    submitIfApproved: true,
    chainId: 1,
  }),
});
 
const editPrepareResult = await editPrepareResponse.json();
 
// If not approved, user needs to sign
if (!editPrepareResult.txHash) {
  const userEditSignature = await userWallet.signTypedData(
    editPrepareResult.signTypedDataParams,
  );
 
  // Send the signed edit data
  const editSendResponse = await fetch("/api/edit-comment/gasless/send", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      signTypedDataParams: editPrepareResult.signTypedDataParams,
      appSignature: editPrepareResult.appSignature,
      authorSignature: userEditSignature,
      edit: editPrepareResult.edit,
      chainId: 1,
    }),
  });
 
  const editSendResult = await editSendResponse.json();
  console.log(editSendResult.txHash);
} else {
  // Already approved and submitted
  console.log(editPrepareResult.txHash);
}
 
// Delete comment - Gasless flow
const deletePrepareResponse = await fetch(
  "/api/delete-comment/gasless/prepare",
  {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      author: "0x1234567890abcdef1234567890abcdef1234567890",
      commentId:
        "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
      submitIfApproved: true,
      chainId: 1,
    }),
  },
);
 
const deletePrepareResult = await deletePrepareResponse.json();
 
// If not approved, user needs to sign
if (!deletePrepareResult.txHash) {
  const userDeleteSignature = await userWallet.signTypedData(
    deletePrepareResult.signTypedDataParams,
  );
 
  // Send the signed delete data
  const deleteSendResponse = await fetch("/api/delete-comment/gasless/send", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      signTypedDataParams: deletePrepareResult.signTypedDataParams,
      appSignature: deletePrepareResult.appSignature,
      authorSignature: userDeleteSignature,
      chainId: 1,
    }),
  });
 
  const deleteSendResult = await deleteSendResponse.json();
  console.log(deleteSendResult.txHash);
} else {
  // Already approved and submitted
  console.log(deletePrepareResult.txHash);
}

Error Handling

400 Bad Request: Invalid request data
404 Not Found: Gasless endpoint not configured
500 Internal Server Error: Server-side error

Development

# Install dependencies
pnpm install
 
# Run development server
pnpm dev
 
# Build for production
pnpm build
 
# Start production server
pnpm start
 
# Type checking
pnpm check-types
 
# Linting
pnpm lint

Best Practices

Security: Keep private keys secure and never expose them in client-side code
Error Handling: Implement proper error handling for all API calls
Rate Limiting: Consider implementing application-level rate limiting to prevent spam
Monitoring: Monitor gas costs and adjust gas limits accordingly
Retry Logic: Implement retry mechanisms for failed transactions
Validation: Always validate comment data before signing
Approval Flow: Use the submitIfApproved flag to optimize gasless flows when users have already approved your app

Additional Resources

See Contract Interactions for manual contract interaction
Check out Post Comment Flows for different comment posting strategies
See Protocol API Reference for contract details
View the Signer App Source Code for implementation details

Signer API Service

Features

Quick Start

Deploy to Vercel

Manual Setup

Environment Variables

Required

Optional

Gasless Configuration

Method Selection

Private Key Method ("private-key")

Privy Method ("privy")

API Endpoints

POST /api/post-comment/sign

POST /api/post-comment/gasless/prepare

POST /api/post-comment/gasless/send

Edit Comment Endpoints

POST /api/edit-comment/sign

POST /api/edit-comment/gasless/prepare

POST /api/edit-comment/gasless/send

Delete Comment Endpoints

POST /api/delete-comment/gasless/prepare

POST /api/delete-comment/gasless/send

Usage Examples

cURL - Standard Signing

cURL - Gasless Prepare

cURL - Gasless Send

cURL - Edit Comment Sign

cURL - Edit Comment Gasless Prepare

cURL - Edit Comment Gasless Send

cURL - Delete Comment Gasless Prepare

cURL - Delete Comment Gasless Send

TypeScript

Error Handling

Development

Best Practices

Additional Resources

Private Key Method (`"private-key"`)

Privy Method (`"privy"`)