Rate Limiting

The 0.link API implements rate limiting to ensure fair usage and maintain service reliability. This guide explains rate limits, how to handle them, and best practices for high-volume applications.

Rate Limit Overview

Rate limits restrict the number of API requests you can make within a specific time window. Limits vary by account plan and endpoint type.

Rate Limit Tiers

Free Tier

• Standard Endpoints: 60 requests per minute
• Upload Endpoints: 10 requests per minute
• Analytics Endpoints: 30 requests per minute

Pro Plan

• Standard Endpoints: 600 requests per minute
• Upload Endpoints: 100 requests per minute
• Analytics Endpoints: 300 requests per minute

Enterprise

• Custom Limits: Negotiated based on needs
• Burst Allowance: Higher temporary limits
• Dedicated Resources: Isolated rate limiting

Rate Limit Headers

Every API response includes rate limit information in headers:

HTTP/1.1 200 OK
X-RateLimit-Limit: 60
X-RateLimit-Remaining: 45
X-RateLimit-Reset: 1642248000
X-RateLimit-Window: 60
X-RateLimit-Type: standard

Header	Description
X-RateLimit-Limit	Maximum requests allowed in window
X-RateLimit-Remaining	Requests left in current window
X-RateLimit-Reset	Unix timestamp when window resets
X-RateLimit-Window	Window duration in seconds
X-RateLimit-Type	Endpoint category (standard, upload, analytics)

Rate Limit Exceeded Response

When you exceed the rate limit, you'll receive a 429 status code:

{
  "status": "error",
  "error": {
    "code": "RATE_LIMIT_EXCEEDED",
    "message": "Too many requests",
    "retry_after": 60,
    "limit": 60,
    "window": "1 minute",
    "endpoint_type": "standard"
  },
  "meta": {
    "timestamp": "2024-01-15T10:30:00Z",
    "request_id": "req_abc123"
  }
}

Handling Rate Limits

Basic Retry Logic

async function makeRequestWithRetry(apiCall, maxRetries = 3) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    try {
      return await apiCall();
    } catch (error) {
      if (error.status === 429) {
        const retryAfter = error.retry_after || Math.pow(2, attempt);
        console.log(`Rate limited. Retrying in ${retryAfter} seconds...`);
        await sleep(retryAfter * 1000);
        continue;
      }
      throw error;
    }
  }
  throw new Error('Max retries exceeded');
}

function sleep(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

Exponential Backoff

async function exponentialBackoff(apiCall, maxRetries = 5) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    try {
      return await apiCall();
    } catch (error) {
      if (error.status === 429 && attempt < maxRetries - 1) {
        const delay = Math.min(1000 * Math.pow(2, attempt), 30000);
        const jitter = Math.random() * 0.1 * delay;
        await sleep(delay + jitter);
        continue;
      }
      throw error;
    }
  }
}

Proactive Rate Limiting

Monitor headers to avoid hitting limits:

class RateLimitedClient {
  constructor(apiKey) {
    this.apiKey = apiKey;
    this.remaining = Infinity;
    this.resetTime = 0;
  }

  async makeRequest(endpoint, options = {}) {
    // Check if we're close to limit
    if (this.remaining < 5 && Date.now() < this.resetTime * 1000) {
      const waitTime = (this.resetTime * 1000) - Date.now();
      console.log(`Proactively waiting ${waitTime}ms to avoid rate limit`);
      await sleep(waitTime);
    }

    const response = await fetch(endpoint, {
      ...options,
      headers: {
        'Authorization': `Bearer ${this.apiKey}`,
        ...options.headers
      }
    });

    // Update rate limit tracking
    this.remaining = parseInt(response.headers.get('X-RateLimit-Remaining'));
    this.resetTime = parseInt(response.headers.get('X-RateLimit-Reset'));

    return response;
  }
}

Best Practices

1. Respect Rate Limit Headers

Always check rate limit headers and adjust request timing:

function checkRateLimit(headers) {
  const remaining = parseInt(headers['x-ratelimit-remaining']);
  const resetTime = parseInt(headers['x-ratelimit-reset']);

  if (remaining < 10) {
    const waitTime = (resetTime * 1000) - Date.now();
    console.warn(`Low rate limit remaining: ${remaining}. Reset in ${waitTime}ms`);
  }
}

2. Implement Graceful Degradation

Design your application to handle rate limits gracefully:

async function fetchDataWithFallback(primaryEndpoint, fallbackData) {
  try {
    return await apiClient.get(primaryEndpoint);
  } catch (error) {
    if (error.status === 429) {
      console.log('Rate limited, using cached data');
      return fallbackData;
    }
    throw error;
  }
}

3. Batch Operations

Group multiple operations to reduce API calls:

// ❌ Individual requests (uses 3 API calls)
const user1 = await client.users.get('user_1');
const user2 = await client.users.get('user_2');
const user3 = await client.users.get('user_3');

// ✅ Batch request (uses 1 API call)
const users = await client.users.getBatch(['user_1', 'user_2', 'user_3']);

4. Cache Responses

Implement caching to reduce API calls:

class CachedApiClient {
  constructor() {
    this.cache = new Map();
    this.cacheTime = 5 * 60 * 1000; // 5 minutes
  }

  async get(endpoint) {
    const cached = this.cache.get(endpoint);
    if (cached && Date.now() - cached.timestamp < this.cacheTime) {
      return cached.data;
    }

    const data = await this.apiCall(endpoint);
    this.cache.set(endpoint, {
      data,
      timestamp: Date.now()
    });

    return data;
  }
}

5. Spread Requests Over Time

Avoid bursts by spreading requests:

async function processItemsWithRateLimit(items, processor, requestsPerMinute = 30) {
  const delay = (60 * 1000) / requestsPerMinute;

  for (const item of items) {
    await processor(item);
    await sleep(delay);
  }
}

Monitoring Rate Limits

Track Usage Patterns

Monitor your rate limit usage:

class RateLimitMonitor {
  constructor() {
    this.requests = [];
  }

  logRequest(endpoint, remaining, limit) {
    this.requests.push({
      endpoint,
      remaining,
      limit,
      timestamp: Date.now(),
      utilization: ((limit - remaining) / limit) * 100
    });

    // Cleanup old data (keep last hour)
    const oneHourAgo = Date.now() - (60 * 60 * 1000);
    this.requests = this.requests.filter(req => req.timestamp > oneHourAgo);
  }

  getUtilizationStats() {
    if (this.requests.length === 0) return null;

    const utilizations = this.requests.map(req => req.utilization);
    return {
      average: utilizations.reduce((a, b) => a + b, 0) / utilizations.length,
      max: Math.max(...utilizations),
      recent: utilizations.slice(-10).reduce((a, b) => a + b, 0) / Math.min(10, utilizations.length)
    };
  }
}

Set Up Alerts

Configure monitoring for rate limit issues:

function checkRateLimitHealth(remaining, limit) {
  const utilization = ((limit - remaining) / limit) * 100;

  if (utilization > 90) {
    console.error('CRITICAL: Rate limit utilization above 90%');
    // Send alert to monitoring system
  } else if (utilization > 75) {
    console.warn('WARNING: Rate limit utilization above 75%');
  }
}

SDK Rate Limiting

Our official SDKs include built-in rate limiting:

JavaScript SDK

import { ZeroLink } from '@0link/sdk';

const client = new ZeroLink({
  apiKey: 'your_api_key',
  rateLimiting: {
    enabled: true,
    strategy: 'exponential_backoff',
    maxRetries: 3
  }
});

// SDK automatically handles rate limits
const projects = await client.projects.list();

Python SDK

from zerolink import Client

client = Client(
    api_key='your_api_key',
    rate_limiting={
        'enabled': True,
        'strategy': 'exponential_backoff',
        'max_retries': 3
    }
)

# SDK automatically handles rate limits
projects = client.projects.list()

Troubleshooting

Common Issues

Consistent 429 Errors

• Check if your request volume exceeds your plan limits
• Implement proper retry logic with exponential backoff
• Consider upgrading your plan

Unexpected Rate Limiting

• Verify you're not making concurrent requests
• Check for automated processes consuming your quota
• Monitor usage patterns in your dashboard

Slow Performance

• Implement caching to reduce API calls
• Use batch endpoints where available
• Optimize request timing and frequency

Getting More Capacity

If you need higher rate limits:

1. Upgrade Plan: Higher tiers include increased limits
2. Contact Sales: Enterprise plans offer custom limits
3. Optimize Usage: Review and optimize your API usage patterns
4. Multiple Keys: Use multiple API keys for different services

Plan Comparison

Feature	Free	Pro	Enterprise
Standard API	60/min	600/min	Custom
Upload API	10/min	100/min	Custom
Analytics API	30/min	300/min	Custom
Burst Allowance	No	2x for 1 min	Custom
Multiple Keys	3	10	Unlimited

Getting Help

For rate limiting questions:

• Dashboard: View usage at dashboard.0link.com
• Support: Email support@0link.com
• Sales: Contact sales@0link.com for higher limits
• Status: Check status.0link.com for service issues