Why we built Centis: a voice notebook for families caring for a parent
The question usually comes in a doctor’s office: “When did the dizziness start?”
You were there for all of it. You drove to every appointment, sat up through the bad nights, and noticed when lunch stopped getting finished. And you can’t answer.
It isn’t that you weren’t paying attention. You were paying attention to everything, and that is the problem. A week of looking after someone produces hundreds of small observations, and none of them come with a place to put them.
Centis is a place to put them. It’s a voice notebook that helps family caregivers keep track of a parent’s health. You talk to it for thirty seconds, often from the car after a visit, and it keeps a dated record in your own words. You can ask it questions, share it with your family, and bring it to the next appointment.
The problem: the record lives in one tired person’s head
When a parent’s health starts to change, one person in the family usually ends up keeping track. Nobody appoints them. It just happens, on top of a job, children and a life.
What they know ends up everywhere and nowhere:
- a text to a brother about a bad night
- a note on a phone about a new pill
- the back of an envelope with a blood pressure reading
- and most of it, nowhere at all — just memory
The information that matters most is the hardest to keep: change over time. “More tired than usual.” “Third time this week.” “She was fine until Saturday.” Memory flattens exactly that, especially when you are worn out.
The obvious fix, writing things down properly, rarely survives a long day. Forms ask for fields nobody has the energy for at ten at night. So the same story gets retold to each sibling, and the important thing gets remembered in the parking lot after the appointment, when it is too late to say.
How Centis works
Centis is a care notebook you talk to. It runs in your phone’s browser at centis.app and is free. You can use it on your own without an account.
- Hold to talk. Say what happened, the way you would tell a friend: “Mom was more tired than usual today, she only ate half her lunch, and I need to call her doctor about the dizziness.”
- Check it. Centis shows what it heard and the lines it wrote. Nothing is saved until you say so. If it misheard a word, fix it, and it can redo the lines from your correction.
- It sorts it for you. Symptoms, food, medication and measurements become dated entries, and anything you need to do becomes a to-do. Only a few things get flagged as worth noting: a fall, a new symptom, a new medication, or your own “I’m not sure whether to worry.”
- Ask it anything. “Has she been dizzy before?” gets an answer from your notes alone, with the dates, and shows you which notes it used.
- See what changed. Open it after a few days away and it shows what is new since you last looked.
- Update your family. It drafts a short message the way you would text a sibling, not a report. You read it and send it yourself.
- Prepare for an appointment. It lays out what happened, newest first, each line dated and in your words, with the questions you said you had. You can hand it across the desk.
What we refused to build
Most of the work on Centis went into what it must not do. A record that gets read back to a doctor is only useful if you can trust every line in it.
It keeps your words. “More tired than usual” stays “more tired than usual”. It never becomes “increased fatigue”. You are not writing a clinical note, and Centis doesn’t pretend you are.
It never adds anything you didn’t say. AI can sound confident while being wrong, so every line Centis writes is checked against what you actually said before you see it. A number you never said, or a symptom you said she didn’t have, is removed, and Centis tells you a line was left out instead of quietly shortening your note. No checker is perfect, which is why you review every note before it is saved.
It never gives medical advice. It won’t tell you whether something is serious, what it might mean, or what to ask the doctor. It reports the record. You and the people treating your family member decide what it means.
It never connects two things. If a new pill started on Saturday and dizziness on Tuesday, you get both, each with its date. You never get “dizzy since the new pill”. That link might be right, or it might send someone to stop a medication. Making it is a conversation for you and the doctor.
When it doesn’t know, it says so. Ask about something that isn’t in your notes and the answer is “I don’t have anything about that yet”, not a guess.
Its dates are honest. If you said on Thursday that something happened on Tuesday, you can move the note to Tuesday. It is then marked date corrected and still shows when you said it. A date that reaches a doctor should say whether the app recorded it or a person set it.
It is private by design. Your notes stay on your device unless you choose a feature that needs them stored on our servers, and we’ll explain what changes before it does. Your voice is turned into text and not kept. When Centis needs to organise a note or answer a question, that text passes through our servers to the AI service that does the work. It isn’t stored by us, and it isn’t used to train AI models. There are no ads and no trackers. The full detail is in our privacy policy.
How Centis differs from other caregiver apps and tools
Nothing else we found is built for this one job: the person keeping track, between appointments, in the few seconds they have. Families already use good tools for nearby jobs, and Centis is meant to sit alongside them, not replace them.
| What families use | What it’s built for | What it leaves out for this job |
|---|---|---|
| A notebook or notes app | Private notes, always to hand | You have to write it up properly, and it can’t answer “when did this start?” |
| A family group chat | Everyone seeing news at once | Observations get buried under logistics, and last month is impossible to find |
| Family update websites | Sending news to a wide circle of friends and relatives | It is a broadcast you write, not a record you can question |
| Care-coordination apps | Organising who brings meals and drives to appointments | It schedules the helpers, not how the person is doing |
| Medication apps | Tracking pills, doses and refills | It covers one slice; the dizziness and the skipped lunch have nowhere to go |
| Patient portals | Showing what the clinic recorded | It is the clinic’s record, with nothing from between visits |
| General AI chatbots | Answering any question | It answers from general knowledge, can offer advice, and keeps no dated record of your notes |
Centis is different in four ways that matter together:
- You talk instead of typing. Thirty seconds of speech, not a form.
- It is a memory you can question. It gives answers with dates, drawn only from what you said.
- It is built not to invent, advise or connect. Those limits are what make it safe to read out in an exam room.
- It belongs to you. You can use Centis on your own without an account. Any feature that needs one, like sharing a record with family, will ask for it.
What Centis is not
We would rather you hear the limits from us than find them yourself.
- It is not medical advice or a medical service. It isn’t offered by a doctor, hospital or health plan, and it doesn’t replace any of them. In an emergency, call emergency services.
- Your notes live on one phone. Without an account, there’s no cloud copy. If you lose the phone or clear the browser, the notes go with it. Add Centis to your home screen, and use Save a copy from time to time.
- It can mishear. Speech recognition makes mistakes, especially with medication names. That is why every note is shown to you before it is saved, and why you can fix it afterwards.
- It is new. Centis is being shaped by the people who use it. If something is wrong, confusing or missing, tell us at hello@centis.app.
Try it after your next visit
The next time you leave a visit, an appointment or a long phone call, open centis.app before you start the car. Hold the button and say how it went. That’s all.
In a few weeks you will have something that’s hard to piece together any other way: a record of what actually happened, in your own words, with the dates. The next time someone asks “when did this start?”, you’ll know.