> ## Documentation Index
> Fetch the complete documentation index at: https://docs.4mica.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Issue a guarantee

> Submit a signed V1 or V2 payment request for BLS certification.

`POST /core/guarantees`

This endpoint verifies the payer signature, request identity, accepted version,
policy, and collateral. V1 guarantees become payable after issuance. V2
guarantees begin in `PENDING_VALIDATION`.

## Authorization

<ParamField path="Authorization" type="string" required post={["header"]}>
  Bearer token with guarantee issuance authority.
</ParamField>

## Request body

<ParamField path="claims" type="object" required />

<ParamField path="claims.version" type="number" required post={["1|2"]} />

<ParamField path="claims.user_address" type="string" required />

<ParamField path="claims.recipient_address" type="string" required />

<ParamField path="claims.req_id" type="string" required>
  Unique request identifier selected before signing.
</ParamField>

<ParamField path="claims.amount" type="string" required>
  Amount in token base units.
</ParamField>

<ParamField path="claims.asset_address" type="string" required>
  <Tooltip headline="ERC-20" tip="Ethereum's standard interface for fungible tokens. It defines common functions for balances, transfers, approvals, and allowances so wallets and applications can interact with tokens consistently.">ERC-20</Tooltip> address, or the zero address for ETH.
</ParamField>

<ParamField path="claims.timestamp" type="number" required />

<ParamField path="claims.validation_policy" type="object" nullable>
  Required for V2 guarantees.
</ParamField>

<ParamField path="signature" type="string" required />

<ParamField path="scheme" type="string" required post={["eip712|eip191"]} />

## Responses

<ResponseField name="claims" type="string" required>
  Hex-encoded BLS certificate claims.
</ResponseField>

<ResponseField name="signature" type="string" required>
  Hex-encoded BLS signature.
</ResponseField>

<RequestExample>
  ```bash cURL theme={null}
  curl -X POST "https://base.sepolia.api.4mica.xyz/core/guarantees" \
    -H "Authorization: Bearer $ACCESS_TOKEN" \
    -H "Content-Type: application/json" \
    -d '{
      "claims": {
        "version": 1,
        "user_address": "0x1111111111111111111111111111111111111111",
        "recipient_address": "0x2222222222222222222222222222222222222222",
        "req_id": "0x1",
        "amount": "0x186a0",
        "asset_address": "0x3333333333333333333333333333333333333333",
        "timestamp": 1782122400
      },
      "signature": "0xUserSignature",
      "scheme": "eip712"
    }'
  ```

  ```javascript title="Fetch" theme={null}
  const response = await fetch(
    "https://base.sepolia.api.4mica.xyz/core/guarantees",
    {
      method: "POST",
      headers: {
        Authorization: `Bearer ${process.env.ACCESS_TOKEN}`,
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ claims, signature, scheme: "eip712" }),
    },
  );
  console.log(await response.json());
  ```

  ```javascript title="Axios" theme={null}
  import axios from "axios";
  const { data } = await axios.post(
    "https://base.sepolia.api.4mica.xyz/core/guarantees",
    { claims, signature, scheme: "eip712" },
    { headers: { Authorization: `Bearer ${process.env.ACCESS_TOKEN}` } },
  );
  console.log(data);
  ```

  ```python Python theme={null}
  import os
  import requests
  body = {"claims": claims, "signature": signature, "scheme": "eip712"}
  headers = {"Authorization": f"Bearer {os.environ['ACCESS_TOKEN']}"}
  url = "https://base.sepolia.api.4mica.xyz/core/guarantees"
  print(requests.post(url, json=body, headers=headers).json())
  ```

  ```go Go theme={null}
  package main
  import ("bytes"; "encoding/json"; "fmt"; "io"; "net/http"; "os")
  func main() {
    body, _ := json.Marshal(map[string]any{
      "claims": claims, "signature": signature, "scheme": "eip712",
    })
    request, _ := http.NewRequest(
      "POST",
      "https://base.sepolia.api.4mica.xyz/core/guarantees",
      bytes.NewReader(body),
    )
    request.Header.Set("Authorization", "Bearer "+os.Getenv("ACCESS_TOKEN"))
    request.Header.Set("Content-Type", "application/json")
    response, _ := http.DefaultClient.Do(request)
    defer response.Body.Close()
    result, _ := io.ReadAll(response.Body)
    fmt.Println(string(result))
  }
  ```
</RequestExample>

<ResponseExample>
  ```json 200 OK theme={null}
  {
    "claims": "0xEncodedCertificateClaims",
    "signature": "0xBlsSignature"
  }
  ```

  ```json 400 Bad Request theme={null}
  { "error": "Invalid signed guarantee request" }
  ```

  ```json 401 Unauthorized theme={null}
  { "error": "Missing or invalid access token" }
  ```

  ```json 403 Forbidden theme={null}
  { "error": "Token is not authorized to issue this guarantee" }
  ```

  ```json 409 Conflict theme={null}
  { "error": "Guarantee identity has already been used" }
  ```
</ResponseExample>

## Status codes

| Code  | Description                                             |
| ----- | ------------------------------------------------------- |
| `200` | Guarantee accepted and BLS certificate issued.          |
| `400` | Claims, policy, signature, or collateral checks failed. |
| `401` | The bearer token is missing or invalid.                 |
| `403` | The token lacks issuance authority.                     |
| `409` | The signed guarantee identity already exists.           |
| `500` | Core could not issue the guarantee.                     |

See [transaction lifecycle](/core-concepts/transaction-lifecycle) for V1 and V2
states and signed fields.