Free AI Agent APIs — Build Autonomous Agents in 2026

March 3, 2026 12 min read AI Agents

Building an AI agent that does more than chat? You need APIs — for LLM inference, persistent memory, web scraping, code execution, crypto wallets, file storage, and more. The problem: most of these cost $29-99/month before you even have users.

We compiled the best free APIs for AI agent developers in 2026 — tools you can integrate into LangChain, CrewAI, LangGraph, or your own agent framework. Every API listed here has a free tier, and most require no signup.

Try them all from one gateway

Agent Gateway unifies 39+ APIs behind a single endpoint. Get an API key and start calling any service instantly.

Explore Agent Gateway

What APIs Do AI Agents Need?

A modern autonomous agent isn't just an LLM prompt. It's a system with multiple capabilities. Here's the API stack most production agents require:

LLM / Reasoning

The brain. GPT-4, Claude, Llama, Mistral — needs an API to send prompts and get completions.

Memory / State

Persistent context across sessions. Key-value stores, vector DBs, conversation history.

Web Access

Search the web, scrape pages, extract structured data. Agents need real-time information.

Code Execution

Run generated code safely in a sandbox. Python, Node.js, shell commands.

File Storage

Upload, download, and manage files. Agents generate artifacts that need persistence.

Communication

Send emails, webhooks, Slack messages. Agents need to notify humans and other systems.

Financial / Crypto

Wallets, payments, DeFi trading. Agents that handle money need secure financial APIs.

Identity / Auth

API keys, JWT tokens, identity management. Multi-agent systems need authentication.

1. Agent Gateway — Unified API for 39+ Services

Our API Free Tier

Instead of integrating 10+ separate APIs, Agent Gateway gives your agent a single endpoint that proxies to 39 specialized services: crypto wallets, DeFi trading, screenshots, code execution, web scraping, file storage, DNS, email, and more.

Why it matters: Your agent makes one authenticated request to /v1/{service}/... and Agent Gateway routes it to the right backend. One API key, one base URL, 39 services.

# Create a free API key (200 credits)
curl -X POST https://agent-gateway-kappa.vercel.app/api/keys/create

{
  "key": "gw_abc123...",
  "credits": 200,
  "services": 39,
  "docs": "/docs"
}

# Use it to call any service through the gateway
curl https://agent-gateway-kappa.vercel.app/v1/crypto-feeds/api/prices \
  -H "Authorization: Bearer YOUR_KEY"

{
  "BTC": {"usd": 94521.00, "change24h": 2.3},
  "ETH": {"usd": 2847.50, "change24h": -0.8},
  "SOL": {"usd": 178.20, "change24h": 5.1}
}

Free tier: 200 credits, no signup
Services: 39 APIs across 9 categories
Docs: OpenAPI 3.1 + Swagger UI on every service
Agent Gateway landing page

2. LLM APIs — The Agent's Brain

Best Free LLM APIs for Agents

Provider	Free Tier	Best Model	Use Case
Anthropic Claude	$5 free credits	Claude Opus 4.6	Complex reasoning, code generation, tool use
Ollama	100% free (local)	Llama 3.3 70B	Privacy-first, offline agents, zero API cost
Hugging Face	Generous free tier	45,000+ models	Specialized models (vision, audio, embeddings)
Groq	Free tier available	Llama 3.3 70B	Ultra-fast inference (500+ tokens/sec)
Agent LLM Ours	Included in gateway	Multi-provider	Privacy-routed LLM calls via Venice AI

For privacy-sensitive agent workloads (wallet lookups, user data), route through a privacy-preserving provider. Our Agent LLM service proxies to Venice AI (zero-logging inference):

# Privacy-first LLM call through Agent Gateway
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-llm/api/chat \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"messages": [{"role": "user", "content": "Analyze this wallet: 0x..."}]}'

3. Crypto Wallet API — Give Agents Financial Capabilities

Our API Free Tier

AI agents that interact with DeFi protocols, manage treasuries, or execute trades need a wallet API. Frostbyte Wallet supports 9 chains (Ethereum, Solana, Base, Arbitrum, Polygon, Optimism, Avalanche, BSC, Fantom).

# Generate an HD wallet for your agent (returns mnemonic + addresses for all chains)
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-wallet/wallets/generate \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json"

{
  "mnemonic": "word1 word2 ... word12",
  "addresses": {
    "ethereum": "0x7a3b...f29e",
    "solana": "ABC...xyz",
    "base": "0x7a3b...f29e"
  }
}

# Check balance on any chain
curl https://agent-gateway-kappa.vercel.app/v1/agent-wallet/wallets/0x7a3b...f29e/balance?chain=ethereum \
  -H "Authorization: Bearer YOUR_KEY"

{
  "address": "0x7a3b...f29e",
  "chain": "ethereum",
  "balance": "0.42",
  "symbol": "ETH"
}

Also available as an MCP server for Claude Desktop and Cursor — see our DeFi MCP setup guide.

4. Memory & State — Persistent Agent Context

Our API Free Tier

Agents need memory that persists across sessions. Our Agent Memory service provides key-value storage with namespaces, TTL, and search:

# Store a memory
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-memory/api/memory \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"key": "user_preferences", "value": {"theme": "dark", "language": "en"}, "namespace": "user_123"}'

# Retrieve it later
curl https://agent-gateway-kappa.vercel.app/v1/agent-memory/api/memory/user_preferences?namespace=user_123 \
  -H "Authorization: Bearer YOUR_KEY"

Open-source alternatives:

Mem0 — Universal memory layer with semantic search. 26% more accurate than OpenAI Memory, 90% fewer tokens.
Chroma — Open-source vector database. Great for RAG-based agent memory.
Redis — Fast key-value store. Battle-tested for session state.

5. Code Execution — Run Agent-Generated Code Safely

Our API Free Tier

When your agent writes code, it needs a sandboxed environment to run it. Agent Coderunner executes Python, Node.js, and shell scripts with timeout protection:

# Execute Python code
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-coderunner/api/execute \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"language": "python", "code": "import math\nprint(math.factorial(20))"}'

{
  "output": "2432902008176640000\n",
  "exitCode": 0,
  "executionTime": 45
}

Open-source alternative: Daytona — Elastic infrastructure for running AI-generated code in secure sandboxes.

6. Web Scraping & Search — Real-Time Information

Our API Free Tier

Agents stuck with training data are useless for real-time tasks. Agent Scraper extracts content from any URL, and Agent Search queries the web:

# Scrape a webpage
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-scraper/api/scrape \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url": "https://news.ycombinator.com", "format": "markdown"}'

# Search the web
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-search/api/search \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"query": "latest ethereum gas prices"}'

Open-source alternatives:

Firecrawl — Web scraping API that converts pages to LLM-ready markdown. Built for AI agents.
Browser-Use — Python library that lets agents control a full browser (click, scroll, fill forms).

7. Screenshot API — Visual Understanding

Our API Free Tier

Agents with vision capabilities need screenshots. Agent Screenshot captures any URL with 5 viewport presets, full-page mode, and dark mode:

# Take a screenshot for visual analysis
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-screenshot/api/screenshot/json \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url": "https://example.com", "viewport": "desktop", "fullPage": true}'

{
  "image": "iVBORw0KGgoAAAA...",
  "format": "png",
  "viewport": {"width": 1280, "height": 720}
}

Pair with a vision-capable LLM (Claude, GPT-4V) to give your agent visual understanding of any webpage. See our full guide: Free Screenshot API for Developers.

8. Webhooks — Agent Communication

Our API Free Tier

Agents need to receive and send HTTP callbacks. Webhook Inspector creates unique URLs that capture incoming requests, perfect for testing integrations and receiving event notifications:

# Create a webhook endpoint
curl -X POST https://agent-gateway-kappa.vercel.app/v1/webhook-inspector/new \
  -H "Authorization: Bearer YOUR_KEY"

{
  "id": "a1b2c3d4e5f6",
  "url": "https://webhook-inspector.../a1b2c3d4e5f6",
  "inspectUrl": "https://webhook-inspector.../inspect/a1b2c3d4e5f6",
  "expiresInHours": 24
}

See our full guide: Free Webhook Testing Tool.

9. File Storage — Persistent Artifacts

Our API Free Tier

Agents generate files — reports, images, code, data exports. Agent Filestorage provides upload/download with unique file IDs:

# Upload a file
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/upload \
  -H "Authorization: Bearer YOUR_KEY" \
  -F "file=@report.pdf"

{
  "fileId": "f_xyz789",
  "filename": "report.pdf",
  "size": 245760,
  "downloadUrl": "/api/files/f_xyz789/download"
}

10. More Agent Infrastructure

Agent Gateway includes 30+ additional services. Here are the most useful for agent developers:

Service	What It Does	Agent Use Case
Agent Email	Send and receive emails	Customer communication, notifications
Agent DNS	DNS lookups and monitoring	Domain verification, uptime monitoring
Agent Scheduler	Cron-like job scheduling	Recurring tasks, timed actions
Agent Transform	Data format conversion	JSON/XML/CSV transformation
Agent Imageproc	Image resize, crop, convert	Thumbnail generation, format optimization
Agent PDFgen	HTML to PDF conversion	Report generation, invoice creation
Agent Shorturl	URL shortening	Shareable links in agent outputs
Agent Identity	JWT token management	Multi-agent authentication
Agent Monitor	Uptime and health checks	Watch external services and APIs
Agent Secrets	Encrypted secret storage	API key management for agent tools
DeFi Trading	Token prices and swaps	Trading bots, portfolio tracking
Onchain Analytics	Blockchain data queries	Wallet analysis, transaction monitoring

Integrating with Agent Frameworks

LangChain / LangGraph

Wrap any Agent Gateway endpoint as a LangChain tool:

from langchain.tools import tool
import requests

GATEWAY = "https://agent-gateway-kappa.vercel.app"
API_KEY = "YOUR_KEY"

@tool
def get_crypto_prices(symbols: str) -> str:
    """Get real-time cryptocurrency prices. Input: comma-separated symbols like 'BTC,ETH,SOL'"""
    resp = requests.get(
        f"{GATEWAY}/v1/crypto-feeds/api/prices",
        headers={"Authorization": f"Bearer {API_KEY}"}
    )
    return str(resp.json())

@tool
def take_screenshot(url: str) -> str:
    """Capture a screenshot of a webpage. Returns base64 image data."""
    resp = requests.post(
        f"{GATEWAY}/v1/agent-screenshot/api/screenshot/json",
        headers={"Authorization": f"Bearer {API_KEY}"},
        json={"url": url, "viewport": "desktop"}
    )
    return resp.json()["image"]

@tool
def run_code(code: str) -> str:
    """Execute Python code in a sandbox. Returns stdout output."""
    resp = requests.post(
        f"{GATEWAY}/v1/agent-coderunner/api/execute",
        headers={"Authorization": f"Bearer {API_KEY}"},
        json={"language": "python", "code": code}
    )
    return resp.json()["output"]

CrewAI

Use the same tools with CrewAI's decorator-based approach:

from crewai import Agent, Task, Crew
from crewai.tools import tool

@tool("Crypto Price Checker")
def check_prices() -> str:
    """Check current cryptocurrency prices"""
    resp = requests.get(
        f"{GATEWAY}/v1/crypto-feeds/api/prices",
        headers={"Authorization": f"Bearer {API_KEY}"}
    )
    return str(resp.json())

analyst = Agent(
    role="Crypto Analyst",
    goal="Monitor crypto markets and identify opportunities",
    tools=[check_prices]
)

crew = Crew(agents=[analyst], tasks=[
    Task(description="Check BTC, ETH, SOL prices and summarize trends", agent=analyst)
])
crew.kickoff()

MCP (Model Context Protocol)

Our DeFi service is available as an MCP server for Claude Desktop and Cursor. Install it for native tool integration:

// claude_desktop_config.json
{
  "mcpServers": {
    "defi": {
      "command": "npx",
      "args": ["-y", "@anthropic/defi-mcp"],
      "env": {
        "API_BASE": "https://agent-gateway-kappa.vercel.app"
      }
    }
  }
}

Full setup guide: How to Add a DeFi MCP Server to Claude and Cursor

Start building your agent now

200 free credits across 39 APIs. Create a key, pick a framework, and ship your agent today.

Get Free API Key

Comparison: Agent Infrastructure Platforms

Feature	Agent Gateway	Composio	Zapier AI	Build Yourself
Free tier	200 credits	Free tier	100 tasks/mo	Free (your infra)
APIs included	39 services	1000+ tools	7000+ apps	You choose
Crypto/DeFi	9 chains, wallets, swaps	Limited	No	Custom
Code execution	Python, Node.js, shell	No	No	Custom sandbox
Signup required	No	Yes	Yes	N/A
Self-hostable	Yes (open source)	Partial	No	Yes
MCP support	Yes	Yes	No	Custom
LangChain integration	REST (any framework)	Native SDK	Connector	Custom
Paid plans from	$0.002/request	$29/mo	$29/mo	$0 + hosting

Building a Complete Agent: End-to-End Example

Here's a Python script that uses Agent Gateway APIs to build a crypto research agent that checks prices, searches the web, and generates a report:

import requests, json

GATEWAY = "https://agent-gateway-kappa.vercel.app"

# Step 1: Get API key
key_resp = requests.post(f"{GATEWAY}/api/keys/create")
API_KEY = key_resp.json()["key"]
headers = {"Authorization": f"Bearer {API_KEY}"}

# Step 2: Get crypto prices
prices = requests.get(
    f"{GATEWAY}/v1/crypto-feeds/api/prices",
    headers=headers
).json()
print(f"BTC: ${prices['BTC']['usd']:,.2f}")
print(f"ETH: ${prices['ETH']['usd']:,.2f}")

# Step 3: Scrape latest news
news = requests.post(
    f"{GATEWAY}/v1/agent-scraper/api/scrape",
    headers=headers,
    json={"url": "https://www.coindesk.com", "format": "text"}
).json()

# Step 4: Store results in agent memory
requests.post(
    f"{GATEWAY}/v1/agent-memory/api/memory",
    headers=headers,
    json={
        "key": "daily_report",
        "value": {"prices": prices, "timestamp": "2026-03-03"}
    }
)

# Step 5: Generate PDF report
pdf = requests.post(
    f"{GATEWAY}/v1/agent-pdfgen/api/generate",
    headers=headers,
    json={"html": f"<h1>Daily Crypto Report</h1><p>BTC: ${prices['BTC']['usd']:,.2f}</p>"}
).json()
print(f"Report generated: {pdf.get('downloadUrl', 'check response')}")

Frequently Asked Questions

How many free API calls do I get?

Agent Gateway gives you 200 free credits with each API key. Each API call costs 1 credit. No signup or credit card required. Paid credits cost $0.002 per request — top up with USDC on Base.

Can I use these APIs with any agent framework?

Yes. All APIs are standard REST endpoints that work with LangChain, CrewAI, LangGraph, AutoGPT, or any custom framework. Just make HTTP requests. We also offer an MCP server for Claude Desktop and Cursor integration.

Is there rate limiting?

Free tier: 30 requests per minute. With an API key: 120 requests per minute. Rate limit headers (X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset) are included in every response.

Which blockchains are supported for crypto/DeFi?

9 chains: Ethereum, Solana, Base, Arbitrum, Polygon, Optimism, Avalanche, BSC, and Fantom. Wallet creation, balance checking, and token swaps are supported on all chains.

Is the code execution sandboxed?

Yes. Agent Coderunner executes code in isolated environments with timeout protection (30 seconds max). Supports Python, Node.js, and shell scripts. No filesystem persistence between executions.

Can I self-host Agent Gateway?

Yes. All services are open-source and can be self-hosted. See the GitHub repositories for deployment instructions. The hosted version is available for free at agent-gateway-kappa.vercel.app.

What's the difference between Agent Gateway and Composio?

Composio focuses on SaaS integrations (Slack, Gmail, Notion) with managed authentication. Agent Gateway focuses on developer infrastructure (code execution, crypto wallets, web scraping, file storage) with no-signup access. They're complementary — use Composio for SaaS tools and Agent Gateway for infrastructure.

Free AI Agent APIs — Build Autonomous Agents in 2026

Try them all from one gateway

What APIs Do AI Agents Need?

LLM / Reasoning

Memory / State

Web Access

Code Execution

File Storage

Communication

Financial / Crypto

Identity / Auth

1. Agent Gateway — Unified API for 39+ Services

Our API Free Tier

2. LLM APIs — The Agent's Brain

Best Free LLM APIs for Agents

3. Crypto Wallet API — Give Agents Financial Capabilities

Our API Free Tier

4. Memory & State — Persistent Agent Context

Our API Free Tier

5. Code Execution — Run Agent-Generated Code Safely

Our API Free Tier

6. Web Scraping & Search — Real-Time Information

Our API Free Tier

7. Screenshot API — Visual Understanding

Our API Free Tier

8. Webhooks — Agent Communication

Our API Free Tier

9. File Storage — Persistent Artifacts

Our API Free Tier

10. More Agent Infrastructure

Integrating with Agent Frameworks

LangChain / LangGraph

CrewAI

MCP (Model Context Protocol)

Start building your agent now

Comparison: Agent Infrastructure Platforms

Building a Complete Agent: End-to-End Example

Frequently Asked Questions

More Developer Resources