data-availability

Multi-chain data availability (SQD)

Query raw and decoded on-chain blockchain data across 113+ networks through the buy gateway at https://gateway.usebuy.ai/sqd.

The gateway proxies requests to the decentralized SQD Network (formerly Subsquid) Portal, providing high-throughput historical and real-time data access without requiring node infrastructure, archive nodes, or chain-specific RPC providers.

Unlike the paid API capabilities under /v1/, the /sqd/ endpoints are completely free — no x402 payment challenge, no signing, and no tokens required.

Non-negotiable boundaries

• Zero cost / No payment: Never call buy_pay_quote or buy curl for /sqd/* routes. Use ordinary curl or standard HTTP fetch.
• IP rate limiting: The free tier enforces token-bucket rate limits per client IP (120 requests/minute, burst 20). If throttled (HTTP 429), read the Retry-After header and wait before retrying.
• Ad-hoc bounded queries only: Request bounded block ranges (fromBlock and toBlock). Do not initiate long-lived persistent streams or webhooks.
• Deterministic finality: For payment verification, deposit tracking, or financial auditing, always use /finalized-stream or /finalized-head rather than unfinalized endpoints to avoid reorganization rollbacks.
• NDJSON parsing: Responses from /stream and /finalized-stream are newline-delimited JSON (NDJSON). Parse each line as an independent JSON object.
• Field selection: Only requested fields are returned. Always specify the exact fields needed under fields (e.g. block: { number: true, timestamp: true }).

Available networks

The gateway serves 113+ active networks:

Ecosystem	Networks
EVM (100+ chains)	ethereum-mainnet, arbitrum-one, base-mainnet, optimism-mainnet, polygon-mainnet, binance-mainnet, avalanche-mainnet, berachain-mainnet, blast-l2-mainnet, celo-mainnet, linea-mainnet, scroll-mainnet, abstract-mainnet, gnosis-mainnet, and testnets.
Solana	solana-mainnet, solana-devnet
Bitcoin	bitcoin-mainnet
Tron	tron-mainnet
DEX / Perpetuals	hyperliquid-fills, hyperliquid-replica-cmds
Substrate / Polkadot	bittensor, astar-substrate, asset-hub-polkadot, asset-hub-kusama

To list all current datasets dynamically:

curl --fail --silent --show-error https://gateway.usebuy.ai/sqd/datasets | jq '.[].dataset'

Quick reference: Core endpoints

All endpoints follow the base URL https://gateway.usebuy.ai/sqd/datasets/{dataset}:

Endpoint	Method	Purpose
/sqd/datasets	GET	List all 113+ available datasets and their real-time status.
/sqd/datasets/{dataset}/metadata	GET	Dataset metadata (start block, aliases, status).
/sqd/datasets/{dataset}/head	GET	Latest unfinalized block number and hash.
/sqd/datasets/{dataset}/finalized-head	GET	Latest finalized block (safe for settlement).
/sqd/datasets/{dataset}/timestamps/{timestamp}/block	GET	Resolve a Unix timestamp (seconds) to the first block at or after it.
/sqd/datasets/{dataset}/stream	POST	Ad-hoc query across blocks, logs, transactions, instructions.
/sqd/datasets/{dataset}/finalized-stream	POST	Query finalized blocks only (zero reorg risk).

---

Use cases & examples

1. Verify a payment or token transfer (EVM)

Check for ERC-20 transfers (e.g. USDC on Arbitrum or Base) to a specific recipient address over a block range:

curl --fail --silent --show-error \
  --request POST \
  --header 'content-type: application/json' \
  --data '{
    "type": "evm",
    "fromBlock": 200000000,
    "toBlock": 200000100,
    "fields": {
      "block": { "number": true, "timestamp": true },
      "log": { "address": true, "topics": true, "data": true, "transactionHash": true }
    },
    "logs": [{
      "address": ["0xaf88d065e77c8cC2239327C5EDb3A432268e5831"],
      "topic0": ["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"],
      "topic2": ["0x000000000000000000000000YOUR_WALLET_ADDRESS_HEX"]
    }]
  }' \
  https://gateway.usebuy.ai/sqd/datasets/arbitrum-one/finalized-stream

2. Verify a Solana token transfer or program interaction

Check for SPL token account balance changes on Solana:

curl --fail --silent --show-error \
  --request POST \
  --header 'content-type: application/json' \
  --data '{
    "type": "solana",
    "fromBlock": 317617480,
    "toBlock": 317617500,
    "fields": {
      "block": { "number": true, "timestamp": true },
      "tokenBalance": { "account": true, "postAmount": true, "postMint": true, "postOwner": true },
      "transaction": { "signatures": true }
    },
    "tokenBalances": [{
      "account": ["RECIPIENT_TOKEN_ACCOUNT_PUBKEY"]
    }]
  }' \
  https://gateway.usebuy.ai/sqd/datasets/solana-mainnet/finalized-stream

Or query Solana program instructions by program ID (e.g. Orca, Raydium, SPL Token):

curl --fail --silent --show-error \
  --request POST \
  --header 'content-type: application/json' \
  --data '{
    "type": "solana",
    "fromBlock": 317617480,
    "toBlock": 317617485,
    "fields": {
      "block": { "number": true },
      "instruction": { "programId": true, "data": true, "accounts": true }
    },
    "instructions": [{
      "programId": ["TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA"]
    }]
  }' \
  https://gateway.usebuy.ai/sqd/datasets/solana-mainnet/stream

3. Check wallet transaction history

Extract recent transactions involving an address across any EVM chain:

curl --fail --silent --show-error \
  --request POST \
  --header 'content-type: application/json' \
  --data '{
    "type": "evm",
    "fromBlock": 10000000,
    "toBlock": 10000500,
    "fields": {
      "block": { "number": true, "timestamp": true },
      "transaction": { "hash": true, "from": true, "to": true, "value": true, "status": true }
    },
    "transactions": [
      { "from": ["0xYOUR_WALLET_ADDRESS"] },
      { "to": ["0xYOUR_WALLET_ADDRESS"] }
    ]
  }' \
  https://gateway.usebuy.ai/sqd/datasets/base-mainnet/stream

4. Timestamp-to-block resolution

Find the exact block or slot number across any network corresponding to a Unix timestamp:

# Ethereum mainnet at timestamp 1710000000 (2024-03-09 16:00:00 UTC)
curl --fail --silent --show-error \
  https://gateway.usebuy.ai/sqd/datasets/ethereum-mainnet/timestamps/1710000000/block
# -> {"block_number": 19398595}

# Solana mainnet at timestamp 1710000000
curl --fail --silent --show-error \
  https://gateway.usebuy.ai/sqd/datasets/solana-mainnet/timestamps/1710000000/block
# -> {"block_number": 252971234}

5. Check chain finality head

Get the latest finalized block number and hash:

curl --fail --silent --show-error \
  https://gateway.usebuy.ai/sqd/datasets/arbitrum-one/finalized-head

---

Response parsing (NDJSON)

Stream endpoints return newline-delimited JSON Lines (application/jsonl), with one block record per line. Parse the output into a standard array:

async function fetchAdHoc(dataset, payload) {
  const res = await fetch(`https://gateway.usebuy.ai/sqd/datasets/${dataset}/stream`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(payload)
  });

  if (res.status === 429) {
    const retryAfter = res.headers.get('Retry-After');
    throw new Error(`Rate limit exceeded. Wait ${retryAfter}s.`);
  }

  if (!res.ok) {
    throw new Error(`HTTP ${res.status}: ${await res.text()}`);
  }

  const text = await res.text();
  const blocks = text
    .trim()
    .split('\n')
    .filter(Boolean)
    .map((line) => JSON.parse(line));

  return blocks;
}

---

Error handling

Status	Cause	Action
400 invalid_request	Malformed JSON or unknown field selector.	Review fields and filter keys against the SQD schema.
404 not_found	Unknown dataset name.	Check dataset list at GET /sqd/datasets.
405 method_not_allowed	HTTP method not permitted.	Only GET and POST are allowed on /sqd/*.
413 body_too_large	Request payload exceeded 64 KB limit.	Narrow filter lists or split queries.
429 rate_limited	Exceeded 120 req/min or burst cap of 20.	Read Retry-After header and wait before retrying.
502 bad_gateway	Upstream SQD network temporarily unreachable.	Retry with exponential backoff.