# QR Code Generator (underscoredone)

> QR Code Generator (underscoredone) is a paid API for AI agents from qr-code-generator.underscoredone.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Converts a list of text strings (URLs, phone numbers, WiFi credentials, plain text, etc.) into base64-encoded PNG QR code images in a single batch call.

## Facts

- Endpoint: POST https://qr-code-generator.underscoredone.com/generate
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/qr-code-generator-underscoredone-d29a7405
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_z4uR1OlHKR5G5vXSxVXuw

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability qr-code-generator-underscoredone-d29a7405 -d '<json body>'
```

Example prompt: Generate QR codes for these three URLs — https://myshop.com, https://myshop.com/menu, and https://myshop.com/contact — at 800 pixels wide with H error correction so they hold up on printed stickers.

## When to prefer this

Use this endpoint when you need to generate one or more QR codes from arbitrary text in a single API call and receive ready-to-use base64 PNG images. Ideal for batch marketing workflows, event ticketing, product labeling, or any scenario requiring programmatic QR code generation without a separate image hosting step.

## Known failure modes

- No non-empty text entries provided — returns an error requiring at least one valid entry
- An individual text entry exceeds 700 characters — that entry is rejected or the whole request fails
- Size parameter outside 100–1200 range — returns a validation error
- Invalid error_correction value (not L, M, Q, or H) — returns a validation error
- Payment not provided or rejected — returns 402 Payment Required

## How this service works

Send a list of texts — website addresses, phone numbers, plain words, WiFi details, anything — and get back a ready-to-use QR code image for each one. Every QR code comes as a base64-encoded PNG you can drop straight into a webpage or save to disk. Great for marketing campaigns, event tickets, product labels, menus, or any situation where you need many QR codes in one go. Empty entries are quietly skipped. Each input is limited to 700 characters. You must send at least one non-empty entry.

## Output

An array of base64-encoded PNG images, one per non-empty input string, each containing a scannable QR code. Empty input entries are silently skipped. The images can be embedded directly in HTML or saved to disk.

## Example request

```json
{
 "size": 600,
 "texts": [
  "https://example.com",
  "https://example.com/about",
  "Contact us at example@example.com"
 ],
 "error_correction": "H"
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "size": {
   "type": "integer",
   "description": "How wide (and tall — QR codes are square) the output image should be, measured in pixels. Must be between 100 and 1200. Defaults to 600 if you leave it out."
  },
  "texts": {
   "type": "array",
   "description": "The list of things you want turned into QR codes — website addresses, phone numbers, plain text, WiFi credentials, anything you like. Each entry must be 700 characters or fewer. Empty entries are skipped. At least one real entry is required."
  },
  "error_correction": {
   "type": "string",
   "description": "How much damage or dirt the QR code can survive and still scan correctly. Choose L (least tough, smallest code), M, Q, or H (most tough, slightly larger code). Defaults to H, which is best for printed labels or stickers."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "count": 2,
  "results": [
   {
    "text": "https://example.com",
    "qr_base64": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAlgAAAJYCAYAAAC+ZpjcAA..."
   },
   {
    "text": "Phone: +1-800-555-0199",
    "qr_base64": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAlgAAAJYCAYAAAC+ZpjcAA..."
   }
  ],
  "api_version": "1.0.0"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/qr-code-generator-underscoredone-d29a7405/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from qr-code-generator.underscoredone.com](https://www.zero.xyz/host/qr-code-generator.underscoredone.com/llms.txt)