Sign Any PDF is built and maintained by one person. Real human replies, usually within 24 hours.
My signature won't save. Make sure you have at least a few MB of free space on your device. Signature data is tiny, but the app writes a backup of your key on first launch.
I bought Pro on my old phone — how do I restore it? Open Settings → Restore Purchases. Sign Any PDF asks Apple for your purchase history and unlocks Pro for free on any device signed into the same Apple ID.
Does Sign Any PDF work in airplane mode? Yes. The app is designed to work without any network. The only time it talks to the internet is during an in-app purchase, which uses Apple's StoreKit.
Is the signature legally binding? Sign Any PDF places a visual signature — the one you drew, typed or imported — onto the page, and flattens it into the exported PDF. It does not apply a cryptographic or certificate-based digital signature, so there is nothing for a recipient to cryptographically verify. Many everyday agreements accept a visual signature, but whether yours does depends on local law and on what the other party requires. For high-stakes legal documents, or anywhere a "qualified electronic signature" is specified, use a notary or a qualified e-signature service.