> ## Documentation Index > Fetch the complete documentation index at: https://docs.hex-api.app/llms.txt > Use this file to discover all available pages before exploring further. # Register an account's deposit receivers > Answers, and keeps, the receivers a deposit to `intent_account` in NEAR Intents carries on its source chain: `deposit_hash`, base58 of `sha256` of `{"account_id":"intents.near","msg":"{\"receiver_id\":\"\"}"}` (what omni rebuilds), and `legacy_hash`, base58 of `sha256("intents.near" ‖ msg)` (old deposits). The backend's `auto_deposit_register`. The account is normalized: an EVM address or a NEAR account is lowercased, a base58 32-byte key (a Solana address) becomes its hex implicit account. Without the database, the hashes are still answered with `status: not_recorded`. ## OpenAPI ````yaml https://mpc.hex-api.app/openapi.json post /bridge/register openapi: 3.1.0 info: title: HEX MPC API version: 1.0.0 summary: HOT bridge signatures and relay, the bridge registry and monitor. description: > The public API of `hex-mpc`, a Cloudflare Worker in front of the HOT MPC nodes. It replaces the old HOT backend's bridge endpoints (`api0.herewallet.app`: `process_bridge_deposit`, `auto_deposit_register`, ...) and HOR (`rpc1.hotdao.ai`, `rpc2.hotdao.ai`). ## Which routes to use - **Credit a deposit to NEAR Intents**: `POST /relay/deposit` with the source tx (or the deposit's fields). The service reads the deposit on its chain, signs it and sends `mt_deposit_call` on NEAR, paying the gas. This is what `process_bridge_deposit` did. - **Pay out withdrawals**: `POST /relay/withdraw` with the chain and the receiver; poll `GET /relay/jobs/{chain}/{id}`. - **Clear a paid withdrawal**: `POST /relay/clear`. - **Submit transactions yourself**: the `Signatures` routes return the MPC signatures only. - **Record what your users do** (optional, for support and recovery): `POST /bridge/register`, `/bridge/deposits`, `/bridge/withdrawals`. Every relay call sends only what holds on chain (a deposit that happened, the payout of a withdrawal omni holds, the clear of a paid one), and each at most once, so retrying a call is safe. ## Conventions - **Bodies** are JSON objects, at most 32 KiB (`/intents/solver`: 128 KiB). A body that is not a JSON object is a `422`, a larger one a `413`. - **Big integers.** Nonces and amounts are answered as decimal strings. In requests they may be decimal strings or JSON integers: integers above 2^53 are read exactly (the bridge's nonces are about 1.8e21), but a decimal string is the safer choice for clients whose JSON encoder uses doubles. - **Nonces** are omni's: `unix seconds * 10^12 + n`. - **Encodings.** omni's token ids, receivers and the bridge signatures are base58; NEAR tx hashes are base58. - **Chain ids.** Chain ids are omni's (`v2_1.omni.hot.tg`), not always the chain's own: EVM chains use their EIP-155 id (Ethereum 1, Optimism 10, BNB 56, Polygon 137, Monad 143, X Layer 196, Base 8453, Arbitrum 42161, Avalanche 43114, ...); the others have omni's numbers: Solana 1001, NEAR 1010, Stellar 1100, TON 1117 (TON v1, 1111, is dead), Juno 4444118, Gonka 4444119. - **Errors** are `{ "detail": "..." }` with an HTTP status (FastAPI's format, kept from HOR), the router's own `404`, `405` and `429` included. Clients should branch on the status and show or log the `detail`. A `5xx` (and a `502`/`503` in particular) is worth retrying with backoff; a `4xx` will answer the same until something changes on chain. - **CORS.** Any origin; the request's `Origin` is echoed with `access-control-allow-credentials: true`, and preflights allow `GET, POST, OPTIONS` with any header. - **Times** in answers are milliseconds since the epoch unless named `*_s` (seconds). ## Rate limits Per client IP (an IPv6 client by its /64), over 60 seconds, counted per Cloudflare location: | Class | Limit | Routes | | --- | --- | --- | | `bridge` | 300 / 60 s | `/withdraw/sign`, `/deposit/sign`, `/clear/sign`, `/relay/*`, `/bridge/*` | | `solver` | 120 / 60 s | `/intents/solver` | `/v1/health`, `/v1/time` and `/openapi.json` are not limited. Over the limit the answer is `429` `{ "detail": "Too many requests" }` with `Retry-After: 60`. ## Load protection The MPC nodes are a fixed quorum: every signature is a round on each of them. So on top of the per-IP limits, every call that reaches the nodes (the `Signatures` routes, and the relay's own signing) is admitted globally, whoever asks: - **Rate per kind of signing**, by default 300 a minute each for withdrawals, deposits and clears: over it, `429` with `Retry-After`. - **Signings at once**, 60 in all, each kind its own share: over it, `503` `MPC nodes are busy, try again shortly` with `Retry-After`. Also `503` with `Retry-After` when the nodes answer `429` or too few of them are up. - **One signing per message.** A signature is kept for a day and answered again (a retry, another client, the relay), and while it is being made a second request waits for it (or gets `503` `This signature is being made, try again shortly` after 45 s). A refusal of the bridge (`400`) is answered again for 5 seconds. - **Refusals before the nodes**: a deposit omni already credited (`400` `Deposit … is already credited`), a withdrawal no payout can land (`400` `Withdrawal … : it can only be refunded`: it pays the token contract itself, the zero address, or a Stellar nonce past its 60 days). Retry a `429` or `503` after its `Retry-After`. servers: - url: https://mpc.hex-api.app description: Production security: [] tags: - name: Relay description: >- The recommended integration: the service sends the bridge's transactions and pays for them. Deposits are credited to NEAR Intents; withdrawals are paid out on their chain and cleared on omni. - name: Signatures description: >- The bridge's MPC signatures, for callers that submit the transactions themselves (HOR-compatible: same bodies, answers and errors). Each signature needs omni's word, and a deposit or clear also its AuthCall on chain, so a caller cannot forge or redirect one. - name: Registry description: >- The bridge registry: what users do on the bridge, as clients report it and as the relay sees it on chain. A post only records a claim: nothing is signed or sent for it, and what the relay reads on chain overrides it. Lookups answer 503 while the registry's database is not configured. - name: Monitor description: Health of every bridge HEX moves funds through, over 24 hours. - name: Intents description: >- NEAR Intents solver relay passthrough, used by HEX/HOT kit to publish signed intents. - name: Service description: Health, time and this document. paths: /bridge/register: post: tags: - Registry summary: Register an account's deposit receivers description: >- Answers, and keeps, the receivers a deposit to `intent_account` in NEAR Intents carries on its source chain: `deposit_hash`, base58 of `sha256` of `{"account_id":"intents.near","msg":"{\"receiver_id\":\"\"}"}` (what omni rebuilds), and `legacy_hash`, base58 of `sha256("intents.near" ‖ msg)` (old deposits). The backend's `auto_deposit_register`. The account is normalized: an EVM address or a NEAR account is lowercased, a base58 32-byte key (a Solana address) becomes its hex implicit account. Without the database, the hashes are still answered with `status: not_recorded`. operationId: registerAccount requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/RegisterRequest' examples: near: summary: A NEAR account value: intent_account: alice.near legacy: summary: The backend's field name value: intent_id: alice.near responses: '200': description: The account's receivers. content: application/json: schema: $ref: '#/components/schemas/RegisterAnswer' examples: ok: summary: Registered now value: status: ok intent_account: alice.near deposit_hash: 6QPkTPp7EKZytMtEuvRmqGBBMMuwf4rrX4JjAoiuCYnT legacy_hash: 8954A4odzWf5YXmUmmGFpjo68ywJk6Jw6PyBf7LfKUMt cached: summary: Registered before value: status: already_cached intent_account: alice.near deposit_hash: 6QPkTPp7EKZytMtEuvRmqGBBMMuwf4rrX4JjAoiuCYnT legacy_hash: 8954A4odzWf5YXmUmmGFpjo68ywJk6Jw6PyBf7LfKUMt '413': $ref: '#/components/responses/PayloadTooLarge' '422': $ref: '#/components/responses/InvalidAccount' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalError' components: schemas: RegisterRequest: type: object description: '`intent_account`, or `intent_id` (the old backend''s name).' properties: intent_account: $ref: '#/components/schemas/IntentAccount' intent_id: $ref: '#/components/schemas/IntentAccount' anyOf: - required: - intent_account - required: - intent_id RegisterAnswer: allOf: - $ref: '#/components/schemas/IntentReceiver' - type: object required: - status properties: status: type: string enum: - ok - already_cached - not_recorded description: >- `ok`: kept now. `already_cached`: kept before. `not_recorded`: no database. IntentAccount: type: string description: >- A NEAR Intents account: a NEAR account (`alice.near`, a 64-hex implicit account), an EVM address, or a base58 32-byte key (a Solana address, taken as its hex implicit account). examples: - alice.near - '0xe4df1d74122c2a7b14481cbdde704fbd0a4f11a2' IntentReceiver: type: object required: - intent_account - deposit_hash - legacy_hash properties: intent_account: type: string description: The account, normalized. deposit_hash: $ref: '#/components/schemas/Base58' description: >- The receiver deposits carry: base58 of `sha256` of the `DepositCallArgs` JSON. legacy_hash: $ref: '#/components/schemas/Base58' description: >- The receiver old deposits carry: base58 of `sha256("intents.near" ‖ msg)`. Error: type: object description: 'Every error: FastAPI''s `{ detail }` with the HTTP status.' required: - detail properties: detail: type: string description: What went wrong, readable. examples: - detail: Nonce was not used on target chain Base58: type: string pattern: ^[1-9A-HJ-NP-Za-km-z]+$ description: Base58 (Bitcoin alphabet). responses: PayloadTooLarge: description: 'The body exceeds 32 KiB (`/intents/solver`: 128 KiB).' content: application/json: schema: $ref: '#/components/schemas/Error' examples: tooLarge: value: detail: Body exceeds 32768 bytes InvalidAccount: description: The account is malformed. content: application/json: schema: $ref: '#/components/schemas/Error' examples: account: value: detail: >- intent_account must be a NEAR account, an EVM address or a base58 key required: value: detail: intent_account is required TooManyRequests: description: >- Over the route's per-IP rate limit (60 s), or, on a route that signs, over the MPC nodes' signing rate (see Load protection). Wait `Retry-After` seconds. headers: Retry-After: $ref: '#/components/headers/RetryAfter' content: application/json: schema: $ref: '#/components/schemas/Error' examples: limited: value: detail: Too many requests signing: value: detail: Too many bridge_deposit signings, try again in 1 s InternalError: description: An unexpected error. Its message is not exposed. content: application/json: schema: $ref: '#/components/schemas/Error' examples: internal: value: detail: Internal Server Error headers: RetryAfter: description: Seconds to wait. schema: type: integer example: 60 ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.