There is no single best tool — but there are criteria that separate a solution you can rely on from one you cannot. Here they are, in the order that matters.
Storing data is the easy part. The hard question is when and how it reaches someone else. Look for a documented, testable release: a time delay with a veto window, a notification to named people, or immediate access for someone you already trust today.
If a provider cannot explain who can decrypt your data, assume the provider can. That is not automatically wrong — but it must be stated plainly instead of hidden behind marketing words like “bank-grade security”.
Erbnis is honest about this: data is encrypted at rest and in transit on European infrastructure, and there is no full client-side zero-knowledge encryption.
A legacy tool has to survive longer than a funding round. Ask for an export that is readable without the app, and check whether a paper fallback exists.
In practice the strongest setup combines them: a password manager for credentials, a handwritten or notarised will for succession, and one place that ties everything together and releases it at the right moment.
Erbnis keeps passwords, accounts, documents and wishes encrypted, and releases each item to the right people at the right time.