Instantly rate limits

Instantly Rate Limits

Overview

Handle Instantly API v2 rate limits. The API returns 429 Too Many Requests when limits are exceeded. Most endpoints follow standard limits. The email listing endpoint has a stricter constraint of 20 requests per minute. Failed webhook deliveries are retried up to 3 times within 30 seconds.

Prerequisites

• Completed instantly-install-auth setup
• Understanding of exponential backoff patterns

Known Rate Limits

Endpoint	Limit	Notes
Most API endpoints	Standard REST limits	Varies by plan
GET /emails	20 req/min	Stricter — email listing
Webhook deliveries	3 retries in 30s	Instantly retries to your endpoint
Background jobs	N/A	Async — poll via GET /background-jobs/{id}

Instructions

Step 1: Exponential Backoff with Jitter

import { InstantlyApiError } from "./src/instantly/client";

interface RetryOptions {
  maxRetries: number;
  baseDelayMs: number;
  maxDelayMs: number;
}

const DEFAULT_RETRY: RetryOptions = {
  maxRetries: 5,
  baseDelayMs: 1000,
  maxDelayMs: 30000,
};

async function withBackoff<T>(
  operation: () => Promise<T>,
  opts: Partial<RetryOptions> = {}
): Promise<T> {
  const { maxRetries, baseDelayMs, maxDelayMs } = { ...DEFAULT_RETRY, ...opts };

  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      return await operation();
    } catch (err) {
      const isRetryable =
        err instanceof InstantlyApiError &&
        (err.status === 429 || err.status >= 500);

      if (!isRetryable || attempt === maxRetries) throw err;

      // Parse Retry-After header if available
      let delay = baseDelayMs * Math.pow(2, attempt);
      delay = Math.min(delay, maxDelayMs);

      // Add jitter (10-30% of delay)
      const jitter = delay * (0.1 + Math.random() * 0.2);
      const totalDelay = delay + jitter;

      console.warn(
        `Rate limited (attempt ${attempt + 1}/${maxRetries}). Waiting ${Math.round(totalDelay)}ms...`
      );
      await new Promise((r) => setTimeout(r, totalDelay));
    }
  }
  throw new Error("Unreachable");
}

Step 2: Request Queue with Concurrency Control

class RequestQueue {
  private queue: Array<() => Promise<void>> = [];
  private running = 0;
  private readonly maxConcurrent: number;
  private readonly delayBetweenMs: number;

  constructor(maxConcurrent = 5, delayBetweenMs = 200) {
    this.maxConcurrent = maxConcurrent;
    this.delayBetweenMs = delayBetweenMs;
  }

  async add<T>(operation: () => Promise<T>): Promise<T> {
    return new Promise((resolve, reject) => {
      this.queue.push(async () => {
        try {
          const result = await withBackoff(operation);
          resolve(result);
        } catch (err) {
          reject(err);
        } finally {
          this.running--;
          this.processQueue();
        }
      });
      this.processQueue();
    });
  }

  private async processQueue() {
    while (this.running < this.maxConcurrent && this.queue.length > 0) {
      const task = this.queue.shift()!;
      this.running++;
      if (this.delayBetweenMs > 0) {
        await new Promise((r) => setTimeout(r, this.delayBetweenMs));
      }
      task();
    }
  }
}

// Usage — add 500 leads with controlled concurrency
const queue = new RequestQueue(3, 300); // 3 concurrent, 300ms gap

for (const lead of leads) {
  queue.add(() =>
    instantly("/leads", {
      method: "POST",
      body: JSON.stringify({ campaign: campaignId, email: lead.email, ...lead }),
    })
  );
}

Step 3: Rate-Limited Email Listing

// The /emails endpoint has a 20 req/min limit
// Use a dedicated throttled fetcher
class ThrottledEmailFetcher {
  private requestTimestamps: number[] = [];
  private readonly maxPerMinute = 18; // leave 2 req margin

  private async waitForSlot() {
    const now = Date.now();
    this.requestTimestamps = this.requestTimestamps.filter(
      (t) => now - t < 60000
    );

    if (this.requestTimestamps.length >= this.maxPerMinute) {
      const oldest = this.requestTimestamps[0];
      const waitMs = 60000 - (now - oldest) + 1000; // +1s buffer
      console.log(`Email API throttle: waiting ${waitMs}ms`);
      await new Promise((r) => setTimeout(r, waitMs));
    }

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

  async listEmails(params: {
    campaign_id?: string;
    is_unread?: boolean;
    limit?: number;
    starting_after?: string;
  }) {
    await this.waitForSlot();

    const qs = new URLSearchParams();
    if (params.campaign_id) qs.set("campaign_id", params.campaign_id);
    if (params.is_unread !== undefined) qs.set("is_unread", String(params.is_unread));
    if (params.limit) qs.set("limit", String(params.limit));
    if (params.starting_after) qs.set("starting_after", params.starting_after);

    return instantly(`/emails?${qs}`);
  }
}

Step 4: Batch Operations Pattern

// Instead of creating leads one-by-one, batch where possible
async function addLeadsBatched(
  campaignId: string,
  leads: Array<{ email: string; first_name?: string }>,
  batchSize = 10,
  delayBetweenBatchesMs = 1000
) {
  let added = 0;
  let failed = 0;

  for (let i = 0; i < leads.length; i += batchSize) {
    const batch = leads.slice(i, i + batchSize);

    const results = await Promise.allSettled(
      batch.map((lead) =>
        withBackoff(() =>
          instantly("/leads", {
            method: "POST",
            body: JSON.stringify({
              campaign: campaignId,
              email: lead.email,
              first_name: lead.first_name,
              skip_if_in_workspace: true,
            }),
          })
        )
      )
    );

    added += results.filter((r) => r.status === "fulfilled").length;
    failed += results.filter((r) => r.status === "rejected").length;

    console.log(`Batch ${Math.floor(i / batchSize) + 1}: ${added} added, ${failed} failed`);

    if (i + batchSize < leads.length) {
      await new Promise((r) => setTimeout(r, delayBetweenBatchesMs));
    }
  }

  console.log(`\nTotal: ${added} added, ${failed} failed out of ${leads.length}`);
}

Error Handling

Error	Cause	Solution
429 on lead import	Too many sequential POSTs	Use batch pattern with delays
429 on email listing	>20 req/min	Use ThrottledEmailFetcher
5xx intermittent	Instantly server overload	Backoff + retry; check status.instantly.ai
Webhook delivery retries exhausted	Your endpoint too slow	Return 200 immediately, process async
Queue memory growing	Too many queued operations	Set max queue size, reject overflow

Resources

• Instantly API v2 Docs
• Instantly Blog: API Rate Limits

Next Steps

For security patterns, see instantly-security-basics.