TerrainDx — A shared map for you and your doctor

Who it's for

This is for you if…

✓You've had symptoms brushed off as “nothing” — but the worry hasn't gone away.
✓You're bouncing between specialists who each look at one piece and hand you back.
✓You're the one keeping track for a parent, partner, or child — and re-telling the whole story at every new visit.
✓AI search hands you a frightening list and you can't tell what to take seriously.
✓You just want to walk into your next appointment organized, and be part of the conversation.

TerrainDx maps the whole landscape of what could be going on — common and rare — and shares it between you and your doctor, so you're working from the same picture instead of a single best guess.

Where TerrainDx fits

Different tools for different moments.

The web is full of helpful health resources. Most are great at what they do — just for different moments. Here's how to think about which to use when.

Dr. Google & AI search Once you have a diagnosis: exploring what it means, basic self-care for a known problem.

Medical information sites Learning about a specific condition, treatment options, what to expect.

Community and support sites Coping, hearing from people living with the same thing.

Wellness and lifestyle sites Habits, nutrition, exercise, long-term care of your body.

TerrainDx is for the moments when your health needs a clearer picture: new or confusing symptoms you want to prepare to discuss with your doctor; a chronic condition you want to document and revisit over time, with AI support; multiple conditions that may be interacting; or curiosity about how to be ready for an unexpected change in your health.

If you've ever sat down to search about new symptoms and walked away feeling worse, you're in good company — that's how most of us experience it. TerrainDx is built for that moment, and the feel is meant to be different.

When you're searching about new symptoms…

Have you ever felt…

With TerrainDx

×…like the longer you search, the more anxious you get?

✓The picture comes into proportion — most of what you're seeing is common and manageable.

×…your stomach drop reading the worst case at the top?

✓The concerning possibilities are rare — and when they appear they're shown in scale next to the everyday ones, with the signs that would make them more or less likely.

×…overwhelmed by names you can't pronounce and don't know which to take seriously?

✓The possibilities are organized by what your doctor would ask about first.

×…defensive walking into your appointment, like you read too much online?

✓Prepared and curious — your map becomes something to look at together.

×…like you're handing over a printed list and hoping your doctor will read it?

✓One tap and your doctor sees the same map you saw — free for them.

×…like you understand less than when you started?

✓You understand more, with the right questions to bring to your doctor.

You don't have to take our word for it. See the example case → and imagine how preparing for your next visit might be different.

Two ways in

For yourself, or for someone you love. Same site, same map.

Many people end up doing both. Build a map for yourself, then run another for a parent or partner you're advocating for.

For yourself

Recurring or vague symptoms. Dismissed or rushed by clinicians. Frightened by ranked-list outputs from general AI tools. TerrainDx organizes the full landscape of possibilities, validates that your concerns are reasonable, and gives you a structured way to communicate with your physician.

For someone you love

The de facto medical project manager — watching a parent bounce between specialists who don't integrate, or advocating for a partner or child. TerrainDx gives you a complete picture to bring to the next specialist, instead of starting from zero each time.

Start a map →

Common questions

Questions patients ask first.

Is TerrainDx a diagnostic tool?

No. TerrainDx illuminates the diagnostic terrain — the full landscape of possibilities your doctor would want to consider — so you and your doctor can work from the same information. Your doctor will help guide you on a diagnostic path toward the help you need.

Should I use this instead of calling my doctor?

No. TerrainDx helps you prepare for the conversation with your doctor. It does not replace that conversation. If you're experiencing a medical emergency, call 911.

What if it shows something scary?

It puts the scary possibility in proportion against everything else. Most of the possibilities on any map are normal and manageable — the few that need faster evaluation are clearly marked, with the signs your doctor would want to know about. You don't have to decide anything alone — that's what your doctor is for.

Do you have a subscription model?

Pricing is structured around what you actually need:

Per-case fee — full access for two weeks: enter, amend, re-run with new information, talk through your map with the ranger, print, and share with your doctor.
After your active period — your case stays as a printable view, available to you permanently until you choose to delete it.
Subscription — extends ranger access, keeps doctor sharing open beyond the two-week window, and lets you add cases for loved ones you're advocating for.

How are you protecting my data?

Your map is yours. We don't sell or share your information. We use industry-standard encryption to protect your data in transit and at rest. You decide who sees your map — it isn't shared with anyone, including your doctor, until you tap to share. You can delete your data at any time.

Who built this?

Paul Foster, MD — a board-certified internist with 25 years of practice and 15 years as an internal medicine residency program director. Meet Dr. Foster →