API reference

Error Handling

Common error codes and how to handle them when using the NoLimitNodes API.

Classify errors by protocol before choosing a retry.

HTTP and JSON-RPC

Signal	Meaning	Your action
HTTP `400`	Invalid HTTP request	Fix the request
HTTP `401`	Missing or invalid key	Replace the credential
HTTP `429`	Request limit reached	Back off
HTTP `500`	Server processing failed	Retry with a limit
HTTP `503`	Service unavailable	Retry with backoff
JSON-RPC `-32601`	Unknown method	Fix the method
JSON-RPC `-32602`	Invalid parameters	Fix parameters

async function rpc(method, params = []) {  const response = await fetch("https://rpc.nln.clr3.org", {    method: "POST",    headers: {      "content-type": "application/json",      "x-api-key": process.env.NLN_API_KEY,    },    body: JSON.stringify({      jsonrpc: "2.0",      id: crypto.randomUUID(),      method,      params,    }),  })   const body = await response.json()  if (!response.ok || body.error) {    throw new Error(body.error?.message ?? `HTTP ${response.status}`)  }  return body.result}

WebSocket

Treat an upgrade failure as an authentication or network error.

After a connected socket closes:

Record the close code.
Reconnect with backoff and jitter.
Send every subscription again.
Replace old subscription IDs.
Read missed state through RPC.

gRPC

Status	Your action
`UNAUTHENTICATED`	Check metadata
`PERMISSION_DENIED`	Check plan or policy
`INVALID_ARGUMENT`	Fix request fields
`NOT_FOUND`	Refresh the topic catalog
`RESOURCE_EXHAUSTED`	Reduce concurrent work
`UNAVAILABLE`	Reconnect with backoff
`INTERNAL`	Retry once and record details

Retry rules

Add random jitter.
Cap total attempts.
Set deadlines.
Do not retry permanent client errors.
Keep transaction retries idempotent.
Never log API keys.