Base64 Auto Preview
Runs locally
Paste an API response (or just a Base64 string) and this tool finds every Base64 value in it, works out whether it is a ZPL label, a PDF or an image, and shows a preview you can download. No need to dig out the field or pick the right converter first.
- Free to use
- No registration
- Runs locally in your browser
- Your data is never uploaded
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Your data is processed locally in your browser and is not uploaded.
Learn more about this tool⌄
How it works
If the input is JSON, every string value is checked; otherwise the whole paste, or any long Base64 run inside the text, is checked. Each value is decoded locally and identified by its content: a PDF starts with %PDF-, an image with its PNG, JPEG, GIF or WebP signature, and a ZPL label is text containing ^XA ... ^XZ. ZPL is rendered with the same renderer as the ZPL Viewer. Nothing is uploaded to a server.
Common use cases
- Previewing the encodedLabel returned by a carrier API such as FedEx without decoding it by hand
- Checking which documents (label, invoice, waybill) a shipping API response actually contains
- Pulling a PDF or image out of a JSON payload found in logs or a database
- Combining several shipment documents (invoice, waybill, customs form) into one PDF to print or file
Frequently asked questions
- Does this upload my response anywhere?
- No. Detection, decoding and rendering all happen in your browser, so labels and shipment data stay on your device.
- Can I combine multiple PDFs into one file?
- Yes. When a response contains more than one PDF (for example a shipment with separate invoice, waybill and customs documents), a "Merge" button appears to combine them into a single downloadable PDF, in the order they were found. Up to 20 PDFs can be merged at once; with more than that, the first 20 are merged and the rest stay available individually.
- What does it recognise?
- ZPL labels, PDF files and PNG, JPEG, GIF and WebP images. Other Base64 values (such as 2D barcode data) are counted but not shown.
- Can I paste something that is not valid JSON?
- Yes. A single Base64 value, a data: URI, a copied fragment such as "encodedLabel": "...", or text with Base64 inside all work.