I'd like to write a blog post together with them about what I believe are the slight differences between the two.

To my understanding, what we are doing is very similar to what they are doing, and we might even use the same backend provider for this service.

The major difference that most users will notice first is that their service is for people who prefer subscriptions, where our service is for people who might prefer usage-based pricing.

Another difference is that we store user conversations client side in the user's local storage, while they store user conversations server-side encrypted. In terms of privacy, this is essentially the same, but in terms of convenience, their architecture is slightly better still since it has much more storage than a regular browser can provide, and because you can use your account for multiple devices and still get the same set of conversations, unlike if you are using local storage only.

We are looking into providing server-side encryption of conversations as well, and hopefully we can build it here in the near future.

If they have any input or corrections on what I've stated I would welcome it.