Apollo Rate Limits

Overview

Implement robust rate limiting and backoff for the Apollo.io API. Apollo uses fixed-window rate limiting with per-endpoint limits. Unlike hourly quotas, Apollo limits are per minute with a burst limit per second. Exceeding them returns HTTP 429.

Prerequisites

• Valid Apollo API key
• Node.js 18+

Instructions

Step 1: Understand Apollo's Rate Limit Structure

Apollo's official rate limits (as of 2025):

Endpoint Category           | Limit/min | Burst/sec | Notes
----------------------------+-----------+-----------+-------------------------------
People Search               | 100       | 10        | /mixed_people/api_search (free)
People Enrichment           | 100       | 10        | /people/match (1 credit each)
Bulk People Enrichment      | 10        | 2         | /people/bulk_match (up to 10/call)
Organization Search         | 100       | 10        | /mixed_companies/search
Organization Enrichment     | 100       | 10        | /organizations/enrich
Contacts CRUD               | 100       | 10        | /contacts/*
Sequences                   | 100       | 10        | /emailer_campaigns/*
Deals                       | 100       | 10        | /opportunities/*

Response headers on every successful call:

• x-rate-limit-limit — max requests per window
• x-rate-limit-remaining — requests remaining in current window
• retry-after — seconds to wait (only on 429 responses)

Step 2: Build a Per-Endpoint Rate Limiter

// src/apollo/rate-limiter.ts
export class SlidingWindowLimiter {
  private timestamps: number[] = [];

  constructor(
    private maxRequests: number = 100,
    private windowMs: number = 60_000,
  ) {}

  async acquire(): Promise<void> {
    const now = Date.now();
    // Remove timestamps outside the window
    this.timestamps = this.timestamps.filter((t) => now - t < this.windowMs);

    if (this.timestamps.length >= this.maxRequests) {
      const oldestInWindow = this.timestamps[0];
      const waitMs = this.windowMs - (now - oldestInWindow) + 100;
      console.warn(`[RateLimit] At capacity (${this.maxRequests}/${this.windowMs}ms). Waiting ${waitMs}ms`);
      await new Promise((r) => setTimeout(r, waitMs));
    }

    this.timestamps.push(Date.now());
  }

  get remaining(): number {
    const now = Date.now();
    this.timestamps = this.timestamps.filter((t) => now - t < this.windowMs);
    return this.maxRequests - this.timestamps.length;
  }
}

// Create limiters per endpoint category
export const limiters = {
  search: new SlidingWindowLimiter(100, 60_000),
  enrichment: new SlidingWindowLimiter(100, 60_000),
  bulkEnrichment: new SlidingWindowLimiter(10, 60_000),
  contacts: new SlidingWindowLimiter(100, 60_000),
  sequences: new SlidingWindowLimiter(100, 60_000),
};

Step 3: Exponential Backoff with Retry-After

// src/apollo/backoff.ts
export async function withBackoff<T>(
  fn: () => Promise<T>,
  opts: { maxRetries?: number; baseMs?: number; maxMs?: number } = {},
): Promise<T> {
  const { maxRetries = 5, baseMs = 1000, maxMs = 60_000 } = opts;

  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      return await fn();
    } catch (err: any) {
      const status = err.response?.status;
      if (status !== 429 && status < 500) throw err;
      if (attempt === maxRetries) throw err;

      // Prefer Retry-After header, fall back to exponential backoff
      const retryAfter = err.response?.headers?.['retry-after'];
      const delayMs = retryAfter
        ? parseInt(retryAfter, 10) * 1000
        : Math.min(baseMs * 2 ** attempt + Math.random() * 500, maxMs);

      console.warn(`[Apollo] ${status} attempt ${attempt + 1}/${maxRetries + 1}, retry in ${Math.round(delayMs / 1000)}s`);
      await new Promise((r) => setTimeout(r, delayMs));
    }
  }
  throw new Error('Unreachable');
}

Step 4: Request Queue with Concurrency Control

// src/apollo/queue.ts
import PQueue from 'p-queue';
import { limiters } from './rate-limiter';

type EndpointCategory = keyof typeof limiters;

const queues: Record<EndpointCategory, PQueue> = {
  search: new PQueue({ concurrency: 5, intervalCap: 10, interval: 1000 }),
  enrichment: new PQueue({ concurrency: 5, intervalCap: 10, interval: 1000 }),
  bulkEnrichment: new PQueue({ concurrency: 2, intervalCap: 2, interval: 1000 }),
  contacts: new PQueue({ concurrency: 5, intervalCap: 10, interval: 1000 }),
  sequences: new PQueue({ concurrency: 3, intervalCap: 5, interval: 1000 }),
};

export async function queuedRequest<T>(
  category: EndpointCategory,
  fn: () => Promise<T>,
): Promise<T> {
  await limiters[category].acquire();
  return queues[category].add(() => fn()) as Promise<T>;
}

Step 5: Monitor Rate Limit Usage via Response Headers

// src/apollo/rate-monitor.ts
import { AxiosInstance, AxiosResponse } from 'axios';

export function attachRateMonitor(client: AxiosInstance) {
  client.interceptors.response.use((response: AxiosResponse) => {
    const limit = response.headers['x-rate-limit-limit'];
    const remaining = response.headers['x-rate-limit-remaining'];

    if (limit && remaining) {
      const pct = Math.round(((parseInt(limit) - parseInt(remaining)) / parseInt(limit)) * 100);
      if (pct >= 80) {
        console.warn(`[Apollo] Rate limit ${pct}% used (${remaining}/${limit} remaining) on ${response.config.url}`);
      }
    }
    return response;
  });
}

Output

• Per-endpoint sliding window rate limiter matching Apollo's actual limits
• Exponential backoff respecting retry-after headers
• PQueue-based request queue with per-second burst control
• Response header monitoring with 80% warning threshold

Error Handling

Scenario	Strategy
429 with retry-after	Wait the specified seconds, then retry
429 without header	Exponential backoff: 1s, 2s, 4s, 8s, up to 60s
Bulk enrichment limited	Use dedicated queue with 2/sec burst limit
Near quota (>80%)	Log warning, defer non-critical requests

Examples

Bulk Search with Rate Limiting

import { queuedRequest } from './apollo/queue';
import { withBackoff } from './apollo/backoff';

const domains = ['stripe.com', 'notion.so', 'linear.app', /* ... */];

const results = await Promise.all(
  domains.map((domain) =>
    queuedRequest('search', () =>
      withBackoff(() =>
        client.post('/mixed_people/api_search', {
          q_organization_domains_list: [domain],
          per_page: 25,
        }),
      ),
    ),
  ),
);
console.log(`Searched ${results.length} domains within rate limits`);

Resources

• Apollo Rate Limits
• API Usage Stats
• p-queue Library

Next Steps

Proceed to apollo-security-basics for API security best practices.