How to Resolve 429 Rate Limit Errors When Sending Prompts to Claude from n8n

1// Key Anthropic rate limit headers to look for:
2// x-ratelimit-limit-requests: 60        (your RPM limit)
3// x-ratelimit-remaining-requests: 0     (none left = RPM exceeded)
4// x-ratelimit-reset-requests: 2025-01-01T00:01:00Z (when it resets)
5// x-ratelimit-limit-tokens: 100000      (your TPM limit)
6// x-ratelimit-remaining-tokens: 0       (none left = TPM exceeded)

1// Code node: Calculate exponential backoff
2const prevRetries = $input.first().json.retryCount || 0;
3const retryCount = prevRetries + 1;
4
5if (retryCount > 5) {
6  throw new Error('Max retries (5) exceeded for Claude API call');
7}
8
9// Exponential backoff: 2s, 4s, 8s, 16s, 32s
10const waitSeconds = Math.pow(2, retryCount);
11
12return [{
13  json: {
14    ...($input.first().json),
15    retryCount,
16    waitSeconds,
17    retryAt: new Date(Date.now() + waitSeconds * 1000).toISOString()
18  }
19}];

1// SplitInBatches settings:
2// Batch Size: 1
3//
4// Wait node settings (in the loop path):
5// Resume: After Time Interval
6// Wait Amount: 1
7// Wait Unit: Seconds
8//
9// Flow: SplitInBatches → Claude → Wait → SplitInBatches (loop input)

1// Error Trigger workflow — Code node
2const errorExecution = $input.first().json;
3const errorMsg = errorExecution.execution?.error?.message || '';
4
5const is429 = errorMsg.includes('429') || errorMsg.includes('rate_limit');
6
7if (!is429) {
8  return [{ json: { retry: false, reason: 'Not a rate limit error' } }];
9}
10
11const workflowData = errorExecution.execution?.data || {};
12const retryCount = (workflowData.retryCount || 0) + 1;
13
14if (retryCount > 3) {
15  return [{ json: { retry: false, reason: 'Max retries exceeded' } }];
16}
17
18return [{
19  json: {
20    retry: true,
21    retryCount,
22    originalPayload: workflowData.originalPayload
23  }
24}];

1const response = $input.first().json;
2const headers = response.$response?.headers || {};
3
4const usage = {
5  rpmLimit: headers['x-ratelimit-limit-requests'] || 'unknown',
6  rpmRemaining: headers['x-ratelimit-remaining-requests'] || 'unknown',
7  tpmLimit: headers['x-ratelimit-limit-tokens'] || 'unknown',
8  tpmRemaining: headers['x-ratelimit-remaining-tokens'] || 'unknown',
9  shouldSlowDown: false
10};
11
12const remaining = parseInt(usage.rpmRemaining);
13const limit = parseInt(usage.rpmLimit);
14if (!isNaN(remaining) && !isNaN(limit) && remaining < limit * 0.1) {
15  usage.shouldSlowDown = true;
16}
17
18return [{ json: { ...response, rateLimitUsage: usage } }];