Ada vs Buoy: the two AI symptom checkers compared head-to-head
Last updated September 3, 2026.
Ada and Buoy are the two names that come up when people want something smarter than the WebMD checklist but are not ready to call a doctor. Both are free, both use conversational AI, and both stop short of diagnosis. The differences are in depth and direction.
How does each one work?
Ada describes itself as an AI-powered symptom assessment optimized by clinicians: a structured interview that asks follow-up questions and adapts to your answers, built on a medical knowledge base, plus a doctor-written medical library for reading up afterward, per its own site. Buoy Health centers on chatting about your symptoms and finding the right care, per its own site, positioning itself as the triage layer that points you toward self-care, a doctor visit, or urgent attention. Ada goes deep on what it might be. Buoy goes practical on what to do about it.
What is the experience like?
Ada feels like a thorough intake: more questions, more structure, a differential-style output ranked for your answers, and a library to fall down afterward. Buoy feels like a conversation with a helpful triage nurse: quicker, aimed at the next step rather than the perfect list. Both are free, both work at 2 AM, and both share the honest limitation of every symptom checker: they know only what you type, and a 2015 BMJ study of symptom checkers found they named the correct diagnosis first only about a third of the time.
Which one should you use?
For a careful, interview-style assessment of a puzzling symptom, Ada. For a quick steer on what kind of care fits, Buoy. For the fullest version, a consult that asks follow-ups, weighs your history, and hands you organized notes for a real clinician, Pymander's free AI doctor consult. Emergencies bypass all of it: call 911. Pymander routes emergency red flags to 911, and its escalation logic is documented in its safety architecture working paper.
What a Pymander AI doctor consult looks like
Illustrative example, not a real member's messages.
Common questions
Is Ada or Buoy more accurate?
Neither publishes a head-to-head verdict, and symptom checkers generally are orientation tools: a 2015 BMJ study found they named the correct diagnosis first only about a third of the time. Ada runs deeper interviews; Buoy focuses on routing you to the right care level.
Is Ada free?
Yes. Ada offers its clinician-optimized AI symptom assessment and its doctor-written medical library for free, per its own site.
Is Buoy free?
Yes. Buoy Health offers its chat-based symptom checking and care guidance for free, per its own site.
Can either one diagnose me?
No. Both produce possibilities and direction, not diagnoses. Only a clinician with your history, an exam, and often tests can diagnose.
What should I do after using a symptom checker?
Treat the output as preparation for a real conversation, not an answer. Write down your symptoms, timeline, and what the checker suggested, and bring it to a clinician. Pymander's free AI doctor consult helps you organize exactly that.
What if it is an emergency?
Skip the checker and call 911. Pymander is built to recognize emergency red flags in your text and direct you to call rather than continue.