Seald is described as 'one-click encryption tool that keeps unwanted eavesdroppers out of your conversations. Our goal is to protect the privacy of Internet users, regardless of their skills or the application on which they communicate' and is an app in the Security & Privacy category. There are six alternatives to Seald for a variety of platforms, including Windows, Mac, Linux, Android and iPhone. The best alternative is VeraCrypt, which is both free and Open Source. Other great apps like Seald are Cryptomator (Freemium, Open Source), Hat.sh (Free, Open Source), FinalCrypt (Free, Open Source) and Encrypted Partition Mounter (Free).
Cryptomator provides transparent, client-side encryption for your cloud. Protect your documents from unauthorized access. Cryptomator on the desktop is free and open source software, so you can rest assured there are no backdoors.
FinalCrypt uses the most unbreakable encryption: "One Time Pad" Encryption and has a well designed graphical user interface and an equally advanced command line interface for large automations. Reasons for choosing FinalCrypt:
An app that encrypts text files using the secure AES (Advanced Encryption Standard) encryption, which is approved in the United States for government documents with the highest level of confidentiality.