Health systems that want software to code most charts without a human coder often compare CodaMetrix and Fathom. Medical coding turns a doctor's note into the billing codes on a claim. Both companies sell autonomous coding, which drafts the codes and sends only the uncertain charts to human coders. CodaMetrix began as an internal project at Mass General Brigham, the Boston health system, and spun out in 2019. Fathom, led by co-founder and CEO Andrew Lockhart, sells to health systems, physician groups, and revenue cycle companies, the firms that run billing for providers.
Health systems that want automated coding on both physician and hospital charts, with human coders reviewing the uncertain ones
Groups that will not let AI code any claim
Health systems and billing companies that want automated coding across large chart volumes
Organizations with no coding leader to own the charts the AI sends back
| Axis | CodaMetrix | Fathom |
|---|---|---|
| Specialties covered | Stronger Radiology, pathology, office and hospital visits, endoscopy, and surgery, with an emergency department module added in 2025. |
Used for emergency department and radiology coding, and the customers KLAS interviewed want it to grow into hospital medicine and surgery. |
| Charts coded with no person involved | Cuts manual coding by 70 percent. | Stronger Every customer KLAS interviewed in 2025 had 90 percent or more of its encounters coded fully and accurately by the AI. |
| Size of its customers | Stronger Customers represent 220 hospitals in 27 states, including 9 of the 20 hospitals on the U.S. News Honor Roll. |
The customers KLAS interviewed were a mix of large health systems and large outpatient centers. |
| How it reads the record | Stronger Its CMX CARE platform looks at the patient's longer record, beyond the single note, when it picks codes. |
Its deep learning models draft codes from each chart's clinical documentation. |
| Support and implementation | Similar Getting coding workflows live scores 7.3, with a collaborative working relationship in KLAS customer interviews. |
Similar Getting coding workflows live scores 7.2, with strong support marks in KLAS customer interviews, though a few rollouts took longer than expected. |
| Knowing what you will pay | Similar Quoted by chart volume, specialty mix, automation target, and integration scope. |
Similar Quoted by chart volume, specialties, services, and integration depth. |
CodaMetrix is for a large health system that wants one automated coding platform across radiology, pathology, surgery, and emergency visits, from a company that started inside a health system. Fathom is for a health system, physician group, or billing company whose first targets are emergency department and radiology charts, and that wants the largest share of those charts coded with no person involved.
Walk away from both if no one on your coding team will own the charts the software sends back, or if your compliance team will not let AI code claims. Walk away from Fathom if complex specialties such as surgery are your first goal, since its customers in KLAS interviews want it to grow there.