A free tool that checks a medical bill against public Medicare rules and gives you a letter to take to the billing office.
A family gets a hospital bill they can't verify.
Unbundle checks it against public Medicare rules.
They get a letter that says what is worth asking about.
The AI only reads your bill into structured data. It never decides what is wrong. Every finding comes from fixed, tested rules built on public data from the Centers for Medicare & Medicaid Services (CMS):
The AI does two small jobs: it reads your bill into structured data, and if you tap “What is this?” on a line, it defines that single billing code in general terms. Fixed code decides every finding, and the wording of each finding comes from fixed templates. The AI cannot add, remove or change a finding or its amount.
You add a photo or PDF of your bill.
AI turns what is printed into line items.
Fixed rules compare the line items with public Medicare data.
You get a letter listing what is worth asking about.
Ten checks: nine rules that look at your bill, plus an optional Good Faith Estimate comparison for people without insurance. Seven run on every bill. Two run only if you upload your insurer's Explanation of Benefits (EOB): Denied, then billed and Balance billing. Balance billing compares what the bill asks you to pay with what the EOB says you owe.
The same service billed more than once on the same day.
Units times price that does not match the amount charged.
Charges dated outside the time you were actually there.
Parts of one procedure billed separately when they should be billed together.
More units billed than Medicare allows for a single visit.
Prices far above what Medicare pays for the same service.
Lump-sum or unlabeled charges that do not say what they were for.
Insurance denied a service, but you were billed the full amount. Needs your insurer's EOB.
The bill asks you to pay more than your insurer's EOB says you owe. Needs your insurer's EOB.
If you are uninsured and were given an estimate before your care, we compare it with your bill and tell you whether the difference may be worth disputing.
We ran every rule against our test bills and compared what it flagged with what we expected.
Duplicate charges
Math errors
Wrong dates
Unbundling
Quantity limits
Price outliers
Vague charges
Denied, then billed
Balance billing
Overall
These results come from 16 synthetic test bills we wrote to exercise each rule, including 6 tricky bills designed to catch false alarms. They show the rules behave as designed, not that they catch every real error. Real bills are messier.
The table covers the nine bill rules. The Good Faith Estimate comparison is not part of it.
Everything the rules use is public.
Releases used: NCCI 2026 Q4 and RVU26A.
Unbundle can sit on your home screen like an app. It is the same website, so nothing extra is stored on your phone.
Unbundle was built by a student for the Congressional App Challenge.