JointSignal

Rheumatoid arthritis diary

An honest record of your rheumatoid arthritis.

Built for RA and nothing else. A minute a day becomes the pattern your rheumatologist can act on: not how you feel in the waiting room, but how you have actually been since they last saw you.

Download on the App Store Works with Apple Health

Free for your first 7 days. Requires iOS 18 or later. Fits iPhone Duo, folded or open. No account, no ads, no tracking. Apple Health is read-only, and nothing you record is ever sent to me.

The daily check-in: today's weather in one row at the top, then pain, overall and fatigue on 0 to 10 scales, and morning stiffness chips.
Page one of the report, laid beside the phone: symptom score, joint counts, and pain, fatigue and overall status over three months.

Only rheumatoid arthritisOne condition, done properly. No dropdown of diagnoses, and no features that exist for someone else's disease.

Built around your rheumatologistEverything you record is shaped to be read in a fifteen-minute appointment.

Never fabricatedA question you skip stays unanswered. It never quietly becomes a zero.

What it tracks

Everything a rheumatologist asks about. Nothing else.

JointSignal is a rheumatoid arthritis symptom tracker for iPhone: everything a rheumatologist asks about, and nothing that exists for some other condition. Screens below are from the app, unretouched.

The daily check-in

A minute a day. One tap each.

Pain, overall status, fatigue, morning stiffness, sleep and mood, each a single tap, with a switch for flare days. Under a minute, by design.

The daily check-in with 0 to 10 scales for pain, overall status and fatigue.

Joint count

Every joint they check. Fingers included.

The 28 joints your rheumatologist scores, plus the neck and both feet, with tap targets built for hands with active RA. Tender, swollen, or both. Self-reported, and labelled that way everywhere it appears.

The joint count: a left hand with three tender and two swollen joints marked, and running totals out of 28.

Apple Health, read-only

Your symptoms, beside Apple Health.

Steps, walking speed, sleep and heart rate sit under what you reported, on one shared axis. Measured by your phone, so unaffected by how you felt that day. The app never writes to Health.

Trends, From Apple Health: daily steps charted over the same weeks as the symptom scores, read from Health and never written to.

Calendar

A missed day is never a good day.

Every day coloured by how bad it was, flares marked, and gaps shown as gaps: the view that shows whether the days you missed were also the worst ones.

A month calendar with each day coloured by pain, flare days marked, and days with no entry left empty.

And the rest of your treatment

Medicines and adherence New in 1.3

Your regimen, dose by dose, on whichever days you take each one, with a note for how to take it, such as a dose that steps up or down over several weeks. Dose changes are marked on every chart, and a dose you never answered is excluded from the percentage, not counted as missed.

Bloods, with reference ranges

CRP and ESR charted beside your symptoms, the rest of your panel kept with its reference ranges, plus appointment and blood-test reminders so a draw never gets missed before a review.

Side effects, logged and tracked

When it started, whether it has settled, and which medicine you suspect, recorded as a suspicion. Timing against your doses is stated as counts, never as cause.

The weather, if you want it

Each day's temperature, humidity and air pressure under your pain score. Off until you turn it on, and the app keeps the weather, never where you were.

Your record, in a form you can question

Export everything as CSV or JSON, and ask an AI assistant such as Claude or ChatGPT what it shows before you see your rheumatologist. How that works.

Backups that happen without you

A dated backup a day to your own iCloud Drive, thirty kept and never overwritten. There is no server to lose it and no account to be locked out of.

The report

Take the guesswork out of rheumatology appointments.

RA is treated to a target: you and your rheumatologist agree where you are trying to get, and adjust treatment until you are there. That only works if they can see how you have actually been between visits, and a short appointment leans almost entirely on what you can remember. JointSignal turns a minute a day into data they can act on.

Report page one: symptom score, self-reported joint counts, and pain, fatigue and overall status charted over three months. Report page two: morning stiffness figures, the current regimen with its schedules and dosing notes, dose adherence, side effects reported, and blood results with reference ranges. Report page three: walking speed, steps and sleep read from Apple Health against the previous period, flare days with dated notes, and the patient's questions listed in order.
Objective patterns, not impressionsMorning stiffness duration, joint counts, flares, adherence and bloods over any date range, beside what your phone measured.
Readable in the roomTwo or three pages, black ink on white paper, built to be read in the time an appointment allows.
Every figure traceableNothing is filled in for you. If you didn't record it, it isn't there.

Before

Walk in with your questions already written.

The moment a question occurs to you is never the moment you are in the room. Save questions as they come, put the one that matters at the top, and they print on the report. In the room, one tap opens a stripped-back view built for reading across a desk, with a place to write down what you were told.

The questions list: three questions to ask, the I'm in the appointment button, and questions already asked with the answers written in.

After · New in 1.3

Walk out with a record of what you raised.

Mark each question asked and add what you were told. Every past appointment then opens as its own record: the questions and answers, the side effects you had around then, the medicines you were on that day, and your blood results since the visit before. Questions you did not get to stay on your list for next time.

A past rheumatology review opened as a record: three questions marked asked, two with the answer written in, then the side effects around that appointment with their dates.

Export the PDF for any date range and email it ahead, AirDrop it at reception, or just hand your phone across the desk. The record of each appointment is read off the dates of what you already entered, so nothing is copied or stored twice.

Read the guide: preparing for a rheumatology appointment

Your data, in your hands

Walk in already knowing what your own record says.

The report is written for your rheumatologist. This part is for you. JointSignal will hand you the whole record as plain files, ready to give to an AI assistant such as Claude or ChatGPT, and you can ask it questions in your own words. You do not need to know anything about spreadsheets.

  • The same rule as the rest of the app. Blanks stay blank, gaps stay gaps, and a score that cannot be fully worked out is left empty. The figures match the report, because they come from the same sums.
  • You choose what goes. Your notes are left out unless you switch them on. Apple Health data, appointments and your clinicians' names are never included.
  • Free, with or without a subscription. Reading, charting and exporting your record never depend on paying.

Questions worth asking before an appointment:

  • “Summarise my last three months in five lines I could read out to my rheumatologist.”
  • “When did my morning stiffness start getting longer, and what else changed around then?”
  • “Given all this, what should I be asking at my next appointment?”
Three more worth asking
  • “How did my pain and joint counts change in the six weeks after my methotrexate dose went up?”
  • “How many flare days did I have each month, and how long did they last?”
  • “Do my worst days line up with falling air pressure? How many days is that based on?”

The last of the first three matters most. Treatment is decided with your rheumatologist, and a short appointment goes better when you arrive with the right questions. Save what comes out of it under Questions, and it prints on your report.

Trends, Weather section: a note that the app draws no conclusion, then a pain chart above an air pressure chart on the same dates.

Does the weather get into your joints? Look for yourself.

Plenty of people with RA are sure it does, and the research is mixed: some large studies find small effects from humidity and falling pressure, others find none. Switch weather on and Trends draws your pain score above air pressure, its change over each day, humidity and temperature, on one time axis. It tells you how many days have both, and stops there. No verdict: a few dozen days of one person's diary can suggest a pattern worth raising, not prove one.

Weather is off until you turn it on. When it is on, the app sends your approximate location, rounded to about 10 km, to Apple’s weather service, and nothing you have recorded goes with it. Your location is never stored.

Two things to keep in mind. An AI assistant can describe patterns in what you recorded. It cannot examine you, it knows nothing about you beyond the file, and it can be confidently wrong, so treat what it says as something to take to your rheumatologist rather than something to act on. And once you give the file to an AI service it has left JointSignal’s hands: what happens to it next is set by that service’s privacy terms, not this app’s, so it is worth checking their settings before you share. JointSignal itself sends the file nowhere.

One rule that doesn't bend

The app never fills in a blank for you.

A question you didn't answer stays unanswered. It never quietly becomes a zero, and a day you missed never appears on a chart as a good day. A report is only useful to a clinician if everything on it is something you actually said.

  • No account, no server. Your record lives on your phone, with a daily backup in your own iCloud Drive. It never comes to me.
  • No analytics, no tracking, no third-party code. Not on your health data, not on anything.
  • Apple Health is read-only. The app requests no write access at all, so it cannot alter your Health record.
  • Your backups are yours. They go to your own iCloud Drive, or to your phone. Never to me.
  • Nothing is ever sold. There is nothing to sell. I don't receive your data in the first place.

Read the full privacy policy

Why it exists

I'm Scott. I have rheumatoid arthritis, and I use JointSignal every day, the same app you can download, to manage it alongside my own rheumatologist.

I went looking for an app that would let me track RA properly and could not find one. The apps I tried covered several conditions rather than one condition well. One left the finger joints out of its joint count, which is a strange omission for an arthritis app. None of them read Apple Health, so the thing my phone already measured all day sat in a separate app from the thing I was typing in every evening. I was paying a subscription for that.

The bigger problem was what those apps thought tracking was for. RA is managed with your rheumatologist, not around them. Appointments are short, they happen a few times a year, and the decisions made in them lean almost entirely on what you can report about the months in between. What helps is the pattern, not the impression: how long the stiffness really lasts in the morning, which joints have been swollen and when, what the fatigue has done over weeks, when the flares came, what you were taking and whether you actually took it.

So I built the app around the appointment: a check-in fast enough to do every day, a record honest enough to hand over, and a report a rheumatologist can read in a minute.

And JointSignal is not a company. It is just me, in Christchurch, New Zealand, building the thing I needed, with far more hours in it than a subscription will ever pay back. The subscription covers the costs of operating the app and keeping it maintained, and your data is worth nothing to me because I never receive it. I'm one person on the same road as you, walking alongside everyone else living with RA, hoping the thing that helps me helps you.

See it before you download.

The check-in that takes a minute, a joint map built for sore hands, charts that leave your missed days as gaps, and the report you hand over. These are the ten screens the App Store shows, each with a line on it to say what you are looking at.

Your RA, on the record: the daily check-in with page one of the report laid over it. A minute a day, one tap each: the check-in, shown half in light and half in dark. Walk in with the whole story: the printed report, three pages deep. Your symptoms, beside Apple Health: steps and exercise minutes under your own scores. Every joint they check, fingers included: the hand map of the 28-joint count. A missed day is never a good day: a month coloured by pain, with gaps left as gaps. See what changed, and when: thirty days of charts with the dose change marked. Is it the weather? See for yourself: pain charted above air pressure on the same dates. Remember what you meant to ask: three questions saved for the next appointment. Private, made by Scott, who has RA: no account, no analytics, and the record stays on the phone.

See it on the App Store

Pricing

The whole app, no tiers. A tracker that withholds your own joint count behind an upgrade is not a tracker.

NZ$69.99 a year

or NZ$6.99 a month

Prices in New Zealand dollars. The App Store shows yours in your own currency.

Free for your first 7 days. Nothing to sign up for.

  • Every feature, including the report
  • Apple Health integration
  • Automatic daily backup to your iCloud
  • No advertising, ever
Download now What the subscription pays for

If your subscription ends, you keep full access to read and export everything you recorded. Your history is never held to ransom against a payment.

Questions

Is this medical advice?

No. JointSignal doesn't diagnose anything and it isn't medical advice. It records what you tell it and shows you the patterns. Your rheumatologist does the rest. Never delay seeking medical attention because of something this app did or did not show you.

What am I actually paying for?

The costs of running the app and keeping it alive. Your data never touches a server of mine. But an app still costs real money and real time to keep going: the domain and website, the developer account, and the ongoing work of new features, security updates, keeping up with each new version of iOS, responding to what people report, and building what is missing. Paying regularly is what makes that an obligation rather than a hobby.

What happens to my data if I stop paying?

You keep it, and you keep full access to read and export all of it. Locking someone out of their own symptom history would contradict the rule the whole app is built on.

What is the symptom score?

Pain, overall status and physical function, each 0–10, totalling 0–30. It is the app's own combined figure and it deliberately has no severity bands — those belong to validated instruments, and the function questions here are the app's own plain-language set. Use it as a trend line: is it going up or down.

Does it calculate DAS28?

Yes, from your self-reported joint counts, and it is labelled self-reported everywhere it appears. DAS28 has published cut-points, so disease activity against a target is reported through it rather than through the app's own figure. It is not a substitute for your rheumatologist examining your joints.

Can I fill in a day I missed?

Within the last week, yes, and the report marks those entries as filled in after the day. Beyond a week the day is read-only. A pain score recalled from further back is a guess, and this app treats a gap as more honest than a guess.

Can I record a medicine I take on several days, or a dose that changes week by week?

Yes. A weekly medicine can be taken on any days you choose, such as three days in a row, and every medicine has a dosing note that shows on Today, in Treatment and on your report, for instructions like a dose that steps up or down over several weeks. Two limits, stated plainly: a medicine taken twice a day is still one tick a day, with the note carrying the detail, and a planned dose step is recorded as a dose change on the day it happens rather than scheduled ahead. You can also set a reminder for any medicine at any time of day, such as an evening one for the second dose of a twice-daily tablet, under Settings → Reminders.

What happens to my questions after the appointment?

Mark them asked, and add what you were told if you want to. Each past appointment opens a record of the questions you asked, the side effects you had around then, the medicines you were on that day and your blood results since the previous visit. Questions you did not get to stay on your list for the next appointment. The record is worked out from the dates of what you entered, so nothing is copied or stored twice.

Which conditions does it cover?

Rheumatoid arthritis, and only that. If you live with a different form of arthritis, this is not the app for you. That focus is what makes it the right one if you live with RA.

Can I use an AI assistant like Claude or ChatGPT with my data?

Yes. Report → Export data gives you everything you have recorded as CSV files or one JSON file, with a short README that explains the scales so the assistant reads them correctly. Share it into the assistant you use and ask questions in plain English. The app sends the file nowhere itself, and once you hand it to an AI service it is covered by that service’s privacy terms rather than this app’s. An assistant can be wrong, and it cannot examine you, so bring what you learn to your rheumatologist rather than acting on it.

Does the weather feature track my location?

No. Weather is off unless you switch it on in Settings. When it is on, the app asks iOS for your approximate location, rounds it to about 10 km, and sends only that to Apple’s weather service to fetch the day’s temperature, humidity and air pressure. Nothing you have recorded goes with it, and your location is never stored: the app keeps the weather, not the place.

Does my data sync between devices?

Not currently. Everything lives on one phone, backed up to your own iCloud Drive. Syncing between devices is a genuinely difficult problem to solve without risking the accuracy of your record, and it will not ship until it can be done without that risk.

Does it work on iPhone Duo?

Yes, on both screens. On the large display, folded open, each screen keeps to a comfortable reading width rather than stretching edge to edge. The layouts are the same ones you would see on any iPhone; there is not yet a separate design that uses the extra space.

Is there an Android version?

No, and there is unlikely to be one. The Apple Health integration is a large part of what the app does.