> ## Documentation Index
> Fetch the complete documentation index at: https://docs.passform.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Barcode types

> Choose a barcode format for your pass and understand each format's code length and character limits

Every pass has a scannable code, set via the pass's `code` field and rendered on the front of the pass. By default this is a QR code, but you can choose a different barcode format per template via the `barcodeFormat` field.

Passform supports the four barcode formats that both Apple Wallet and Google Wallet render natively: **QR**, **PDF417**, **Aztec**, and **Code128**. Apple Wallet's barcode support is limited to exactly these four formats, so restricting to this set guarantees every format works on both wallets with no fallback or platform-specific behavior.

`barcodeFormat` is set on the **template**, not the individual pass — every pass issued from a template renders its code in that template's chosen format. The `code` value itself remains a per-pass field; see [Updating passes](/guides/updating-passes) for how to set or change it.

## Choosing a format

| `barcodeFormat` value | Format     | Best for                                                                                                                                                                 |
| --------------------- | ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `QR` *(default)*      | QR code    | General purpose. Highest data capacity, scannable from any angle, and the most widely recognized format.                                                                 |
| `PDF417`              | PDF417     | Compact 2D stacked barcode. Common on boarding passes and ID cards.                                                                                                      |
| `Aztec`               | Aztec code | Compact 2D barcode that doesn't require a quiet zone (blank margin) around it, making it a good fit for smaller pass designs. Widely used for transit and event tickets. |
| `Code128`             | Code128    | Traditional 1D (linear) barcode. Use this if your scanning hardware is linear-barcode-only — 2D formats are unreadable by 1D-only scanners.                              |

Set it when creating or updating a template:

```json theme={null}
{
  "type": "offer",
  "title": "Summer Sale Voucher",
  "barcodeFormat": "PDF417",
  "issuerName": "Acme Co",
  "foregroundColor": "#FFFFFF",
  "backgroundColor": "#1a1a2e",
  "icon": "https://cdn.example.com/icon.png",
  "logo": "https://cdn.example.com/logo.png",
  "banner": "https://cdn.example.com/banner.png"
}
```

If omitted, `barcodeFormat` defaults to `QR`.

## Code length and character limits

Each format has a different data capacity, and 1D formats additionally restrict which characters they can encode reliably. Passform validates a pass's `code` against its template's `barcodeFormat` when the pass is created or updated, and rejects a `code` that doesn't fit.

| `barcodeFormat` |    Max length    | Character set                                        |
| --------------- | :--------------: | ---------------------------------------------------- |
| `QR`            | 2,000 characters | Any                                                  |
| `PDF417`        |  800 characters  | Any                                                  |
| `Aztec`         | 1,500 characters | Any                                                  |
| `Code128`       |   48 characters  | Printable ASCII only (no emoji or non-Latin scripts) |

<Note>
  These limits are set well below each format's theoretical maximum capacity to keep the resulting barcode reliably scannable at typical wallet-pass size. A longer, denser code is technically encodable but becomes harder for a scanner to read reliably at that size.
</Note>

If a `code` violates the selected format's limit, the API returns a `400` error and the pass is not created or updated:

```json theme={null}
{
  "statusCode": 400,
  "message": "Pass code is not valid for the template's barcode format (Code128): must be 1-48 characters and match printable ASCII."
}
```

<Tip>
  Switching an existing template's `barcodeFormat` to a stricter format (for example, from `QR` to `Code128`) does not retroactively validate codes already issued on existing passes — only future creates and updates are checked. Confirm your existing `code` values fit the new format's limits before switching.
</Tip>