Two of the best-known names in clinical documentation, Tandem and Heidi, have both moved beyond the scribe and into clinical decision support. Tandem launched clinical decision support inside Ask Tandem; Heidi launched Heidi Evidence, an evidence layer it built after acquiring the UK company AutoMedica. On paper they answer the same question — help clinicians find and apply trusted medical knowledge — but they take different routes on regulation, sourcing and, most consequentially for UK clinicians, availability.
Regulatory posture
Tandem has been explicit about climbing the regulatory ladder. Its AI scribe, coding assistant and clinical decision support are all CE marked under EU MDR as Class IIa medical devices, externally assessed by a notified body. For a decision-support product, that is a meaningful, independently checked baseline.
Heidi's position is more layered. Its AI scribe is registered with the MHRA as a Class I device for summarisation functionality. Heidi Evidence, however, is newer, and independent coverage has noted that its UK regulatory status is still to be confirmed. So while both companies hold device registrations for their scribes, Tandem currently carries the firmer regulatory footing specifically for its decision-support product.
Sourcing and evidence integrity
Both lean hard on cited answers, and both make a point of source transparency.
Heidi Evidence is built in partnership with named clinical sources — HealthPathways, EMGuidance, MIMS, Vidal, NICE and BMJ Group — and is positioned as ad-free, providing concise summaries with transparent citations and verbatim excerpts. Heidi has framed this explicitly against ad-supported consumer AI, arguing that the integrity of clinical evidence should be non-commercial. It also lets clinicians upload their own sources, and is built in part on Anthropic's Claude models.
Tandem's CDS draws on national guidelines plus locally uploaded protocols, and is designed to use the context of the documented visit. Its evidence story is anchored less in named content partnerships and more in the regulatory assurance of its Class IIa assessment.
Both are new enough that real-world clinical validation is still emerging; neither should be treated as having a long published track record in decision support yet.
The decisive factor for UK clinicians: availability
This is where the comparison stops being academic. Heidi Evidence reportedly began blocking UK NHS email addresses at enrolment in May 2026 — part of a wider pattern in which several clinical AI tools have stepped back from UK NHS access amid regulatory uncertainty. Tandem's CDS, by contrast, is available to selected customers across Europe and the UK.
The result is a paradox worth naming: Heidi Evidence is built on UK-relevant sources like NICE and BMJ Group, yet reportedly excludes UK NHS clinicians at sign-up, while Tandem — a Swedish company — has pursued the higher regulatory class and stayed in the UK market.
| Dimension | Tandem CDS | Heidi Evidence |
|---|---|---|
| Product type | In-consultation decision support | Evidence layer (standalone or with scribe) |
| Regulatory class | CE marked EU MDR Class IIa (notified-body assessed) | Scribe is MHRA Class I; Evidence regulatory status reportedly TBC |
| Sourcing | National guidelines + local uploaded protocols | NICE, BMJ, MIMS, Vidal, HealthPathways, EMGuidance; user uploads |
| Commercial model | Enterprise / EHR-integrated | Free for individual clinicians; ad-free |
| UK NHS availability | Available (selected UK customers) | Reportedly blocking UK NHS emails at enrolment (May 2026) |
| Clinical validation | Emerging | Emerging |
Where iatroX sits
For a UK clinician, the practical question is not only "which decision-support tool is best?" but "which one can I actually use, grounded in UK practice?" iatroX is built around that gap: it is a UK-registered, MHRA-listed Class I clinical AI, free to use, grounded in NICE, CKS, SIGN and the SmPC.
iatroX is deliberately a different layer from Tandem's in-consultation CDS — it informs the clinician's own judgement rather than automating or directing the decision, which is why it sits at Class I rather than Tandem's Class IIa. But unlike Heidi Evidence, it remains available to UK NHS clinicians, and unlike US-centric tools, it is built for UK guidelines from the ground up. The point is not that iatroX out-regulates anyone — Tandem's Class IIa is a higher bar — but that the UK knowledge layer is one a clinician can open today. And Class I being self-declared does not mean ungoverned: iatroX's registration is backed by a full clinical risk-management file and safety case, independently reviewed.
Frequently asked questions
Is Heidi Evidence available to UK NHS clinicians? According to independent reporting, Heidi Evidence began blocking UK NHS email addresses at enrolment in May 2026. UK clinicians should check current availability directly, as the position may change.
How does Tandem's CDS differ from Heidi Evidence on regulation? Tandem's clinical decision support is CE marked under EU MDR as a Class IIa device, externally assessed by a notified body. Heidi's scribe is MHRA Class I, but the regulatory status of Heidi Evidence specifically has been reported as still to be confirmed.
Are these tools clinically validated? Both are recent, and real-world clinical validation for their decision-support products is still emerging. Neither has a long published evidence base in decision support yet, so claims should be read with that in mind.
What is the UK-available alternative? iatroX is a free, UK-registered (UKCA-marked Class I) clinical AI grounded in NICE, CKS, SIGN and the SmPC, and remains available to UK NHS clinicians as a knowledge and reference layer.