Free File Storage API for Developers

Need to upload and share files programmatically? Whether you're building a file-sharing feature, storing AI-generated outputs, handling user uploads in a SaaS app, or sharing temporary build artifacts — you need a file storage API that's simple, fast, and doesn't require configuring S3 buckets.

Setting up AWS S3, managing IAM policies, configuring CORS, and handling presigned URLs adds complexity that slows down development. We built a free file storage API with 3 upload methods, auto-expiring links, download limits, and direct shareable URLs. No signup, no bucket configuration, no cloud console.

Quick Start: Upload a File in One Command

1. Upload via curl (no API key needed for free tier)

# Upload any file with a PUT request
curl -X PUT https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/upload/report.pdf \
  --upload-file report.pdf

{
  "id": "f_17b7f20d0dd4",
  "token": "9f22922553107298",
  "originalName": "report.pdf",
  "contentType": "application/pdf",
  "size": 45230,
  "uploadedAt": "2026-03-03T20:07:59.187Z",
  "expiresAt": "2026-03-04T20:07:59.187Z",
  "ttlHours": 24,
  "downloads": 0,
  "downloadUrl": "/api/files/f_17b7f20d0dd4/download",
  "directUrl": "/d/9f22922553107298/report.pdf"
}

2. Share the direct URL

The directUrl is a public link — anyone with it can download the file, no authentication needed. Perfect for sharing with teammates, clients, or embedding in docs.

3. Download or manage

# Download by file ID (authenticated)
curl https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/f_17b7f20d0dd4/download -o report.pdf

# Delete when done
curl -X DELETE https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/f_17b7f20d0dd4 \
  -H "Authorization: Bearer YOUR_KEY"

3 Upload Methods

Features

API Reference

Code Examples

# Upload a file (raw binary — simplest method)
curl -X PUT https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/upload/screenshot.png \
  --upload-file screenshot.png

# Upload with tags and custom TTL (base64 method)
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/upload/base64 \
  -H "Content-Type: application/json" \
  -d '{"filename": "config.json", "content": "eyJrZXkiOiJ2YWx1ZSJ9", "contentType": "application/json", "tags": ["config", "v2"], "ttlHours": 48}'

# Upload via multipart form (like an HTML form)
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/upload \
  -F "file=@document.pdf"

# List your files
curl https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files \
  -H "Authorization: Bearer YOUR_KEY"

# Set download limit (one-time download link)
curl -X PATCH https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/f_abc123 \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"maxDownloads": 1}'

import requests
import base64

API = "https://agent-gateway-kappa.vercel.app/v1/agent-filestorage"

# Step 1: Get free API key
key_resp = requests.post(f"{API}/api/keys/create")
api_key = key_resp.json()["key"]
print(f"API Key: {api_key}")

headers = {"Authorization": f"Bearer {api_key}"}

# Step 2: Upload a file (multipart)
with open("report.pdf", "rb") as f:
    resp = requests.post(
        f"{API}/api/files/upload",
        headers=headers,
        files={"file": ("report.pdf", f, "application/pdf")}
    )
result = resp.json()
print(f"Uploaded: {result['id']}")
print(f"Share URL: {result['directUrl']}")
print(f"Expires: {result['expiresAt']}")

# Upload from memory (base64)
data = {"hello": "world"}
content = base64.b64encode(json.dumps(data).encode()).decode()
resp = requests.post(
    f"{API}/api/files/upload/base64",
    headers=headers,
    json={
        "filename": "data.json",
        "content": content,
        "contentType": "application/json",
        "tags": ["output", "json"]
    }
)
print(f"JSON uploaded: {resp.json()['directUrl']}")

# List all files
files = requests.get(f"{API}/api/files", headers=headers).json()
for f in files.get("files", []):
    print(f"  {f['originalName']} ({f['size']} bytes, expires {f['expiresAt']})")

const fs = require('fs');

const API = 'https://agent-gateway-kappa.vercel.app/v1/agent-filestorage';

async function uploadFiles() {
  // Step 1: Get free API key
  const keyResp = await fetch(`${API}/api/keys/create`, { method: 'POST' });
  const { key } = await keyResp.json();
  console.log(`API Key: ${key}`);

  // Step 2: Upload via raw binary
  const fileBuffer = fs.readFileSync('report.pdf');
  const resp = await fetch(`${API}/api/files/upload/report.pdf`, {
    method: 'PUT',
    headers: {
      'Authorization': `Bearer ${key}`,
      'Content-Type': 'application/pdf'
    },
    body: fileBuffer
  });
  const result = await resp.json();
  console.log(`Uploaded: ${result.id}`);
  console.log(`Share: ${result.directUrl}`);

  // Step 3: Upload JSON from memory (base64)
  const data = { metrics: [1, 2, 3], timestamp: Date.now() };
  const b64 = Buffer.from(JSON.stringify(data)).toString('base64');
  const jsonResp = await fetch(`${API}/api/files/upload/base64`, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${key}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      filename: 'metrics.json',
      content: b64,
      contentType: 'application/json',
      tags: ['metrics']
    })
  });
  console.log(`JSON uploaded: ${(await jsonResp.json()).directUrl}`);
}

uploadFiles();

Use Cases

CI/CD Build Artifacts

Upload build outputs, test reports, and coverage files from your CI pipeline. Share direct download links in pull request comments or Slack channels. Files auto-expire after 24 hours so you don't accumulate stale artifacts.

# In your CI pipeline — upload test results
RESULT=$(curl -s -X PUT https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/upload/test-report.html \
  --upload-file coverage/report.html)
URL=$(echo $RESULT | python3 -c "import sys,json; print(json.load(sys.stdin)['directUrl'])")
echo "Test report: $URL"

AI Agent Output Storage

When your AI agent generates a report, creates an image, or produces a data file — store it via the API and return the shareable link. The agent doesn't need to manage cloud storage credentials.

Temporary File Sharing

Share files that automatically disappear. Set expiration from 1 hour to 7 days. Optionally set a download limit of 1 for true one-time download links — the file becomes inaccessible after a single download.

# One-time download link (file deleted after first download)
curl -X POST https://agent-gateway-kappa.vercel.app/v1/agent-filestorage/api/files/upload/base64 \
  -H "Content-Type: application/json" \
  -d '{"filename": "secret.txt", "content": "VG9wIHNlY3JldCBkYXRh", "tags": ["sensitive"], "maxDownloads": 1}'

User Upload Backend

Add file upload to your web or mobile app without configuring S3, managing IAM, or writing presigned URL logic. Use the multipart endpoint — it works like a standard HTML form upload.

Comparison: File Storage APIs in 2026

* file.io is free but files are deleted after a single download. Agent File Storage gives you configurable download limits, longer TTLs, and full CRUD operations.

Frequently Asked Questions

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