How Duoheart works, in about four minutes a day

The description fits in a sentence. Each day both partners get the same five questions, you each answer on your own, and nothing is visible until both of you have written. Then the answers open together.

Everything else in the product exists to protect that one mechanism.

Pairing

You invite one person. They accept. That is the entire social graph.

There is no way for anyone else to join, no way to be discovered, and no way for a stranger to contact either of you. Nobody has followers.

This is a constraint rather than a feature set that has not been built yet. A product that can hold two people cannot become something else later.

The five questions

They arrive each day, the same for both of you. Some are light and some are not, and the mix is deliberate, because a product that is serious every day gets used for three weeks.

You do not have to answer all five. Couples who answer one on a bad day and all five on a Sunday are using it correctly.

The questions are not the product. The order of operations is: both write, then both read.

Holding the answers

This is the part that matters and the part that is easy to underestimate.

In conversation, whoever answers second answers differently. Not dishonestly. They adjust: they soften a disagreement, they match a mood, they notice that the first answer was generous and become generous in return. Everyone does this and almost nobody notices doing it.

Holding both answers until both are written removes the effect entirely. There is no first and second. When the answers open, each of you is reading something written without reference to the other.

It also removes the advantage of being faster, which in most couples belongs permanently to the same person.

Threads

Every question opens into a thread, so an answer can become a conversation rather than an entry in a log.

Most do not, and that is fine. The ones that do are usually the ones neither of you expected.

What else is in it

A private chat for the two of you. An optional voice call. An optional weather radar, which exists because people asked for it and which is the least explicable feature in the product.

The app is available in sixteen languages and follows each device, so two people can use it in different languages at the same time.

What it is not

Not a dating app. It is for the relationship you already have.

Not a social network. No feed, no followers, no discovery, no public profile.

Not therapy, and not a substitute for it.

Privacy, briefly

Questions, answers, messages and calls are encrypted on the devices with a key generated there that never reaches our servers. We cannot read what a couple writes.

The costs of that are ours to carry: we cannot recover your content if the key is lost, and our support cannot look at what you wrote in order to help you with it.

What it costs

The first fifty couples to pair are founding couples and keep it free for as long as the service exists.

After that it is a subscription, and only one partner pays. Both are covered, which is the only arrangement that makes sense for a product two people share, and the reason it works is that the entitlement lives on our side rather than in either app store.