Agent skill

API Integration Specialist

Expert in integrating third-party APIs with proper authentication, error handling, rate limiting, and retry logic. Use when integrating REST APIs, GraphQL endpoints, webhooks, or external services. Specializes in OAuth flows, API key management, request/response transformation, and building robust API clients.

View SKILL.md on GitHub Repository
Stars 23,776
Forks 2,298

Install this agent skill to your Project

npx add-skill https://github.com/davila7/claude-code-templates/tree/main/cli-tool/components/skills/development/api-integration-specialist

SKILL.md

API Integration Specialist

Expert guidance for integrating external APIs into applications with production-ready patterns, security best practices, and comprehensive error handling.

When to Use This Skill

Use this skill when:

  • Integrating third-party APIs (Stripe, Twilio, SendGrid, etc.)
  • Building API client libraries or wrappers
  • Implementing OAuth 2.0, API keys, or JWT authentication
  • Setting up webhooks and event-driven integrations
  • Handling rate limits, retries, and circuit breakers
  • Transforming API responses for application use
  • Debugging API integration issues

Core Integration Principles

1. Authentication & Security

API Key Management:

javascript
// Store keys in environment variables, never in code
const apiClient = new APIClient({
  apiKey: process.env.SERVICE_API_KEY,
  baseURL: process.env.SERVICE_BASE_URL
});

OAuth 2.0 Flow:

javascript
// Authorization Code Flow
const oauth = new OAuth2Client({
  clientId: process.env.CLIENT_ID,
  clientSecret: process.env.CLIENT_SECRET,
  redirectUri: process.env.REDIRECT_URI,
  scopes: ['read:users', 'write:data']
});

// Get authorization URL
const authUrl = oauth.getAuthorizationUrl();

// Exchange code for tokens
const tokens = await oauth.exchangeCode(code);

2. Request/Response Handling

Standardized Request Structure:

javascript
async function makeRequest(endpoint, options = {}) {
  const defaultHeaders = {
    'Content-Type': 'application/json',
    'Authorization': `Bearer ${apiKey}`,
    'User-Agent': 'MyApp/1.0.0'
  };

  const response = await fetch(`${baseURL}${endpoint}`, {
    ...options,
    headers: { ...defaultHeaders, ...options.headers }
  });

  if (!response.ok) {
    throw new APIError(response.status, await response.json());
  }

  return response.json();
}

Response Transformation:

javascript
class APIClient {
  async getUser(userId) {
    const raw = await this.request(`/users/${userId}`);

    // Transform external API format to internal model
    return {
      id: raw.user_id,
      email: raw.email_address,
      name: `${raw.first_name} ${raw.last_name}`,
      createdAt: new Date(raw.created_timestamp)
    };
  }
}

3. Error Handling

Structured Error Types:

javascript
class APIError extends Error {
  constructor(status, body) {
    super(`API Error: ${status}`);
    this.status = status;
    this.body = body;
    this.isAPIError = true;
  }

  isRateLimited() {
    return this.status === 429;
  }

  isUnauthorized() {
    return this.status === 401;
  }

  isServerError() {
    return this.status >= 500;
  }
}

Retry Logic with Exponential Backoff:

javascript
async function retryWithBackoff(fn, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await fn();
    } catch (error) {
      if (!error.isAPIError || !error.isServerError()) {
        throw error; // Don't retry client errors
      }

      if (i === maxRetries - 1) throw error;

      const delay = Math.pow(2, i) * 1000; // 1s, 2s, 4s
      await sleep(delay);
    }
  }
}

4. Rate Limiting

Client-Side Rate Limiter:

javascript
class RateLimiter {
  constructor(maxRequests, windowMs) {
    this.maxRequests = maxRequests;
    this.windowMs = windowMs;
    this.requests = [];
  }

  async acquire() {
    const now = Date.now();
    this.requests = this.requests.filter(t => now - t < this.windowMs);

    if (this.requests.length >= this.maxRequests) {
      const oldestRequest = this.requests[0];
      const waitTime = this.windowMs - (now - oldestRequest);
      await sleep(waitTime);
      return this.acquire();
    }

    this.requests.push(now);
  }
}

const limiter = new RateLimiter(100, 60000); // 100 requests per minute

async function rateLimitedRequest(endpoint, options) {
  await limiter.acquire();
  return makeRequest(endpoint, options);
}

5. Webhook Handling

Webhook Verification:

javascript
function verifyWebhookSignature(payload, signature, secret) {
  const expectedSignature = crypto
    .createHmac('sha256', secret)
    .update(payload)
    .digest('hex');

  return crypto.timingSafeEqual(
    Buffer.from(signature),
    Buffer.from(expectedSignature)
  );
}

app.post('/webhooks/stripe', express.raw({ type: 'application/json' }), (req, res) => {
  const signature = req.headers['stripe-signature'];

  if (!verifyWebhookSignature(req.body, signature, process.env.STRIPE_WEBHOOK_SECRET)) {
    return res.status(401).send('Invalid signature');
  }

  const event = JSON.parse(req.body);
  handleWebhookEvent(event);

  res.status(200).send('Received');
});

Integration Patterns

REST API Client Pattern

javascript
class ServiceAPIClient {
  constructor(config) {
    this.apiKey = config.apiKey;
    this.baseURL = config.baseURL;
    this.timeout = config.timeout || 30000;
  }

  async request(method, endpoint, data = null) {
    const options = {
      method,
      headers: {
        'Authorization': `Bearer ${this.apiKey}`,
        'Content-Type': 'application/json'
      },
      timeout: this.timeout
    };

    if (data) {
      options.body = JSON.stringify(data);
    }

    const response = await retryWithBackoff(() =>
      fetch(`${this.baseURL}${endpoint}`, options)
    );

    return response.json();
  }

  // Resource methods
  async getResource(id) {
    return this.request('GET', `/resources/${id}`);
  }

  async createResource(data) {
    return this.request('POST', '/resources', data);
  }

  async updateResource(id, data) {
    return this.request('PUT', `/resources/${id}`, data);
  }

  async deleteResource(id) {
    return this.request('DELETE', `/resources/${id}`);
  }
}

Pagination Handling

javascript
async function* fetchAllPages(endpoint, pageSize = 100) {
  let cursor = null;

  do {
    const params = new URLSearchParams({
      limit: pageSize,
      ...(cursor && { cursor })
    });

    const response = await apiClient.request('GET', `${endpoint}?${params}`);

    yield response.data;

    cursor = response.pagination?.next_cursor;
  } while (cursor);
}

// Usage
for await (const page of fetchAllPages('/users')) {
  processUsers(page);
}

Best Practices

Security

  • Store API keys in environment variables or secrets management
  • Use HTTPS for all API calls
  • Verify webhook signatures
  • Implement request signing for sensitive operations
  • Rotate API keys regularly

Reliability

  • Implement exponential backoff retry logic
  • Handle rate limits gracefully
  • Set appropriate timeouts
  • Use circuit breakers for failing services
  • Log all API interactions for debugging

Performance

  • Cache responses when appropriate
  • Batch requests when the API supports it
  • Use streaming for large responses
  • Implement connection pooling
  • Monitor API usage and costs

Monitoring

  • Track API response times
  • Alert on error rate increases
  • Monitor rate limit consumption
  • Log failed requests with context
  • Set up health checks for critical integrations

Common Integration Examples

Stripe Payment Processing

javascript
const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY);

async function createPaymentIntent(amount, currency = 'usd') {
  return await stripe.paymentIntents.create({
    amount,
    currency,
    automatic_payment_methods: { enabled: true }
  });
}

SendGrid Email Sending

javascript
const sgMail = require('@sendgrid/mail');
sgMail.setApiKey(process.env.SENDGRID_API_KEY);

async function sendEmail(to, subject, html) {
  await sgMail.send({
    to,
    from: process.env.FROM_EMAIL,
    subject,
    html
  });
}

Twilio SMS

javascript
const twilio = require('twilio')(
  process.env.TWILIO_ACCOUNT_SID,
  process.env.TWILIO_AUTH_TOKEN
);

async function sendSMS(to, body) {
  await twilio.messages.create({
    to,
    from: process.env.TWILIO_PHONE_NUMBER,
    body
  });
}

Troubleshooting

Authentication Issues

  • Verify API keys are correctly set
  • Check token expiration
  • Ensure proper OAuth scopes
  • Validate signature generation

Rate Limiting

  • Implement client-side rate limiting
  • Use batch endpoints when available
  • Spread requests over time
  • Consider upgrading API tier

Timeout Errors

  • Increase timeout values for slow endpoints
  • Implement request cancellation
  • Use streaming for large payloads
  • Check network connectivity

When integrating APIs, prioritize security, reliability, and maintainability. Always test error scenarios and edge cases before production deployment.

Recommended Agent Skills

Expand your agent's capabilities with these related and highly-rated skills.

davila7/claude-code-templates

verl-rl-training

Provides guidance for training LLMs with reinforcement learning using verl (Volcano Engine RL). Use when implementing RLHF, GRPO, PPO, or other RL algorithms for LLM post-training at scale with flexible infrastructure backends.

23,776 2,298
Explore
davila7/claude-code-templates

openrlhf-training

High-performance RLHF framework with Ray+vLLM acceleration. Use for PPO, GRPO, RLOO, DPO training of large models (7B-70B+). Built on Ray, vLLM, ZeRO-3. 2× faster than DeepSpeedChat with distributed architecture and GPU resource sharing.

23,776 2,298
Explore
davila7/claude-code-templates

gguf-quantization

GGUF format and llama.cpp quantization for efficient CPU/GPU inference. Use when deploying models on consumer hardware, Apple Silicon, or when needing flexible quantization from 2-8 bit without GPU requirements.

23,776 2,298
Explore
davila7/claude-code-templates

Claude Code Guide

Master guide for using Claude Code effectively. Includes configuration templates, prompting strategies "Thinking" keywords, debugging techniques, and best practices for interacting with the agent.

23,776 2,298
Explore
davila7/claude-code-templates

qdrant-vector-search

High-performance vector similarity search engine for RAG and semantic search. Use when building production RAG systems requiring fast nearest neighbor search, hybrid search with filtering, or scalable vector storage with Rust-powered performance.

23,776 2,298
Explore
davila7/claude-code-templates

behavioral-modes

AI operational modes (brainstorm, implement, debug, review, teach, ship, orchestrate). Use to adapt behavior based on task type.

23,776 2,298
Explore

Didn't find tool you were looking for?

Be as detailed as possible for better results