Before you print
How big should it be?
Rule of thumb: printed width ≥ scanning distance ÷ 10. Pick the surface above and the studio sizes the code for you, then checks the printed module size against what a press can actually hold.
Questions people actually ask
Developers and technical teams moving small blobs between systems: keys and tokens for offline transfer, compact binary configs, signed payloads a custom app verifies on scan. If you just want people to read text, the plain text type is simpler.
'Encode my text' takes plain text and converts it to Base64 for you. 'I already have Base64' validates data that is already encoded (standard RFC 4648 with = padding) and puts it in the code untouched.
A QR code holds about 2,900 bytes at the lowest error-correction level, and Base64 inflates data by about a third — so roughly 2 KB of original binary is the practical ceiling, less if you raise error correction. Smaller codes scan faster and print more forgivingly.
No — it is only an encoding, and anyone who scans the code can decode it instantly. If the data is sensitive, encrypt it first and encode the ciphertext; the code itself is generated entirely in your browser, so nothing touches UseQR's servers either way.
Want the detail? How base64 QR codes work — the payload format, what scanners do with it, and where it breaks.