Upload and Share via StableUpload

Upload any local file to S3-backed cloud storage via x402 micropayments. Returns a public URL. No API keys needed.

Setup

See rules/getting-started.md for installation and wallet setup.

Quick Reference

All uploads expire after 6 months.

Workflow

1. Check wallet balance

npx agentcash@latest wallet info

Ensure sufficient USDC balance for the chosen tier. If balance is low, show the deposit link.

2. Determine the tier

Pick the smallest tier that fits the file. Check file size first with ls -la or wc -c.

3. Buy the upload slot

npx agentcash@latest fetch https://stableupload.dev/api/upload -m POST -b '{"filename": "report.pdf", "contentType": "application/pdf", "tier": "10mb"}'

Parameters:

• filename — name for the uploaded file (required)
• contentType — MIME type (required, advisory for browser)
• tier — "10mb", "100mb", or "1gb" (required)

Response:

{
  "uploadId": "k7gm3nqp2",
  "uploadUrl": "https://f.stableupload.dev/k7gm3nqp2/report.pdf?t=...",
  "publicUrl": "https://f.stableupload.dev/k7gm3nqp2/report.pdf",
  "expiresAt": "2026-08-19T00:00:00.000Z",
  "maxSize": 10485760
}

4. Upload the file via curl

Use Bash to PUT the file to the returned uploadUrl:

curl -s -X PUT "<uploadUrl>" -H "Content-Type: <mime>" --data-binary @/absolute/path/to/file

Critical: Use --data-binary (not -d) to preserve binary content. Use the absolute path.

5. Share the public URL

Present the publicUrl to the user. This URL is publicly accessible immediately and remains live for 6 months.

Common MIME Types

Listing Previous Uploads

To list uploads for the current wallet:

npx agentcash@latest fetch https://stableupload.dev/api/uploads

Get Upload Details

npx agentcash@latest fetch https://stableupload.dev/api/download/k7gm3nqp2

Key Details

• No API keys required — payment is the authentication
• Upload URLs expire in 1 hour — upload promptly after buying the slot
• Public URLs last 6 months from purchase date
• Any file type accepted — contentType is advisory for the browser, not a restriction
• S3-backed — files stored on AWS S3 with public read access
• Discovery endpoint: npx agentcash@latest discover https://stableupload.dev if you need to verify endpoints

Common Patterns

Upload a file the user just created: Skip discovery, go straight to wallet check + buy slot + upload.

Upload multiple files: Buy separate slots for each file. Slots can be purchased in parallel but uploads must use the correct uploadUrl for each.

User asks to "share" or "send" a file: Upload it and present the public URL. The URL can be shared anywhere.

Host images for emails: Upload the image, then reference the publicUrl in email HTML:

<img src="https://f.stableupload.dev/abc/photo.png" alt="Photo" />

Error Handling

• Insufficient balance: Show the deposit link from npx agentcash@latest wallet info
• File too large for tier: Suggest the next tier up
• Upload URL expired: Buy a new slot (the previous payment is non-refundable)
• curl fails: Verify the file path exists and the uploadUrl is correctly quoted