Developer guide
The Best Healthcare APIs in 2026: Clinical AI, EHR and Drug Data
Ten APIs developers use to build clinical products — what each does, how to get access, what it costs and how it handles patient data. The EvidenceMD API ranks first for clinical reasoning.
By the Clinical Decision teamUpdated
Quick answer
The best healthcare API for clinical reasoning in 2026 is the EvidenceMD API. It is built for medical reasoning: it works through the case step by step and cites the evidence for each step, while most clinical AI tools focus on evidence search [1]. It is OpenAI-compatible and priced at a flat $0.20 to $0.25 per request with evidence retrieval included [1]. For EHR data, start with Epic on FHIR and Oracle Health's FHIR APIs, or Redox to reach many EHRs through one integration [2] [3] [4]; for drug data, the NLM RxNorm API and openFDA cost nothing [5] [6].
- Pick by layer. Clinical AI, EHR data, integration and reference data are different problems, and most products need more than one.
- A BAA is the gate for patient data. Azure includes HIPAA coverage in its standard terms, AWS and Anthropic offer self-serve BAAs, Google Cloud and OpenAI offer BAAs to customers, and EvidenceMD signs one at API onboarding [7] [8] [9] [10] [11] [1].
- A general model is not a clinical API. A frontier model under a BAA still needs retrieval, citation and clinical evaluation built around it; the EvidenceMD API returns them in one call [1].
- OpenEvidence publishes no self-serve developer API that we could find in October 2026; its integrations are enterprise deals inside Epic [12].
EvidenceMD at a glance
- What it is
- A clinical reasoning AI for healthcare professionals: it searches peer-reviewed evidence, works through the case step by step and cites the source for each step.
- Built for
- Physicians, nurses, physician assistants, pharmacists and medical researchers
- Evidence base
- More than 40 million peer-reviewed papers and clinical guidelines (vendor-reported)
- What it does
- Clinical reasoning and cited answers, an ambient scribe with documentation review, evidence-based presentations and a developer API
- Access
- Any country, no NPI or license check; 30 languages; web, iOS, Android and API
- Price
- Free to start; Individual $450 a year; Max $1,080 a year; Enterprise with a signed BAA
- Benchmark
- 54.6% on HealthBench Hard (self-reported)
- Website
- evidencemd.ai
At a glance
| API | Layer | Access | Price | Patient data |
|---|---|---|---|---|
| EvidenceMD API | Clinical reasoning AI | Self-serve API key; no NPI | $0.20–$0.25 per request | BAA signed at onboarding; zero retention (vendor-reported) |
| Epic on FHIR | EHR data (FHIR R4) | Developer sandbox; each Epic customer enables production | open.epic APIs at no cost (vendor-reported) | Governed by each customer |
| Azure OpenAI in Microsoft Foundry | General models | Any Azure customer | Per token | HIPAA BAA in Microsoft's standard terms |
| Amazon Bedrock | General models | Any AWS account | Per token | BAA accepted in AWS Artifact |
| Anthropic Claude API | General models | Open sign-up | Per token | BAA self-serve in the Console for most organizations |
| Google Gemini Enterprise Agent Platform and MedGemma | General and open medical models | Google Cloud customers; MedGemma weights downloadable | Per token; MedGemma weights at no cost | Google Cloud BAA; MedGemma needs your validation |
| OpenAI API | General models | Open sign-up | Per token | BAA for eligible customers |
| Redox | EHR integration | Sales contract | Not published | HIPAA and HITRUST r2 (vendor-reported) |
| NLM RxNorm API and openFDA | Drug and safety data | Open; no key for RxNorm, optional key for openFDA | No charge | Public data; no patient data needed |
| Oracle Health Millennium APIs | EHR data (FHIR R4) | Developer program; each customer gates production | Not confirmed | Governed by each customer |
What are the main kinds of healthcare API?
Healthcare APIs come in four layers — clinical AI such as the EvidenceMD API, EHR data through FHIR, integration platforms such as Redox, and reference data such as RxNorm and openFDA:
| Layer | What it does | Examples |
|---|---|---|
| Clinical AI | Answers clinical questions, reasons through cases, drafts documentation | EvidenceMD API; general models on Azure, AWS, Google, Anthropic and OpenAI |
| EHR data | Reads and writes patient records through FHIR | Epic on FHIR, Oracle Health Millennium APIs |
| Integration | Connects one application to many EHRs and data formats | Redox |
| Reference data | Drug names, labels, interactions and adverse events | NLM RxNorm, openFDA, DailyMed, FDB MedKnowledge, Medi-Span |
Most clinical products combine layers: a FHIR API to read the chart, a reference-data API to normalize medications, and a clinical AI API to reason over both. The EvidenceMD API is designed to be that last layer — send the case, receive a reasoned answer with citations [1].
The 10 best healthcare APIs, ranked
Ranked on what a clinical product team needs: usefulness out of the box, clear access, published pricing and patient-data terms. The EvidenceMD API ranks first because it is the clinical layer itself — retrieval, reasoning and citations in one OpenAI-compatible call — rather than a component you build one from.
EvidenceMD API
Best clinical reasoning API: a cited, step-by-step clinical answer in one OpenAI-compatible call.
- Best for
- Clinical decision support, differential and workup, prior-authorization drafting and patient education inside your product
- Access
- Self-serve API key with starter credits; no NPI or license check [1]
- Price
- Flat per request: $0.20 (evidencemd-fast, evidencemd-pro) or $0.25 (evidencemd-deep), retrieval and citations included; no monthly minimum
Point the OpenAI SDK at EvidenceMD's endpoint and choose evidencemd-fast, evidencemd-pro or evidencemd-deep. Each request retrieves evidence for that question and returns an answer with inline peer-reviewed citations; set include_thinking to stream the clinical reasoning before the answer [13]. A specialty parameter, JSON mode and 30 output languages come from the same endpoint, with a default limit of 60 requests a minute [1].
EvidenceMD states zero retention of prompts and responses, no training on customer data, AES-256-GCM encryption at rest and hosting on Microsoft Azure (East US 2), with a BAA signed at onboarding before patient data flows (vendor-reported) [1]. The same engine is available as an MCP server for Claude, Claude Code, Cursor and Codex [14].
Strengths
- Clinical retrieval, reasoning and citations in one call
- OpenAI-compatible, so integration is a base-URL change
- Flat per-request price with retrieval included
- 30 output languages from one endpoint
Limits
- Citations arrive inline in the answer text, not as a separate sources array
- Streamed reasoning is English-only
- Text only, with no audio endpoint; SOC 2 Type II in progress
Epic on FHIR
Best route to EHR data at the largest US EHR vendor.
- Best for
- Apps that read or write patient data at Epic organizations
- Access
- Developer sign-up with a sandbox; each Epic customer must enable your app for production [2]
- Price
- open.epic APIs offered at no cost, per Epic (vendor-reported); listing fees vary [15]
Epic on FHIR documents FHIR R4 APIs (plus STU3 and DSTU2) with SMART on FHIR app launch and a sandbox of example data [2]. Epic describes more than 750 no-cost APIs and interfaces on open.epic, including APIs for the CMS-0057 prior-authorization rule (vendor-reported) [15].
A common pattern pairs it with a clinical AI layer: read the problems, labs and medications through FHIR, then send them to the EvidenceMD API for a cited assessment.
Strengths
- Large installed base
- Standards-based FHIR R4
- Free developer sandbox
Limits
- Production access depends on each Epic customer
- Fees beyond the sandbox not clearly published
Azure OpenAI in Microsoft Foundry
Best general-model platform for HIPAA coverage by default.
- Best for
- Teams building their own clinical layer on OpenAI and other models inside Azure
- Access
- Any Azure customer [16]
- Price
- Per token
Microsoft includes a HIPAA BAA through its Product Terms and Data Protection Addendum, so nothing extra has to be signed [7]. Prompts and outputs are not shared with OpenAI or used to train foundation models, data is encrypted at rest with optional customer-managed keys, and eligible customers can apply for modified abuse monitoring [16].
It supplies models, not clinical answers: retrieval, citation and clinical evaluation are yours to build. EvidenceMD is itself hosted on Microsoft Azure.
Strengths
- BAA included by default
- Enterprise controls and keys
- Choice of models
Limits
- Global and DataZone deployments may process data outside your geography
- Preview features can carry different terms
Amazon Bedrock
Best for choosing among many models under one AWS BAA.
- Best for
- AWS-based teams that want several model families behind one contract
- Access
- Any AWS account; accept the AWS BAA self-serve in AWS Artifact [8]
- Price
- Per token
Bedrock and Bedrock AgentCore are on AWS's HIPAA-eligible services list, updated 15 October 2026, alongside Transcribe (including HealthScribe), Comprehend Medical and HealthLake [8].
As with any general platform, retrieval and clinical evaluation are yours to build; teams that want them included call the EvidenceMD API alongside Bedrock.
Strengths
- Many model families
- Self-serve BAA
- Adjacent HIPAA-eligible health services
Limits
- Patient data only in HIPAA-eligible services
- No clinical retrieval built in
Anthropic Claude API
Best general-model API for self-serve HIPAA readiness.
- Best for
- Teams building on Claude models directly
- Access
- Open sign-up; most organizations accept the standard BAA in the Claude Console [9]
- Price
- Per token
Anthropic separates HIPAA readiness from zero data retention: most organizations can accept the standard BAA themselves in the Console, after which encryption, access controls and audit logging apply to protected health information. Enabling HIPAA readiness is permanent, and features such as code execution and beta features are not covered [9].
Clinicians and developers who use Claude can also call EvidenceMD inside it through EvidenceMD's MCP server [14].
Strengths
- Self-serve BAA for most organizations
- Clear list of covered features
Limits
- HIPAA readiness cannot be switched off
- Some features ineligible for patient data
- No patient data in JSON schemas
Google Gemini Enterprise Agent Platform and MedGemma
Best for open medical models you can fine-tune.
- Best for
- Teams that want to host and adapt their own medical model
- Price
- Per token on the platform; MedGemma weights at no cost, hosting paid
Vertex AI became part of the Gemini Enterprise Agent Platform on 22 April 2026 [18], and generative AI on the platform is on Google Cloud's HIPAA covered-products list [10]. MedGemma is a family of open medical text and image models built on Gemma 3, with 4B multimodal and 27B variants; MedGemma 1.5 adds CT, MRI and pathology inputs [17]. Google's Cloud Healthcare API, for FHIR, HL7v2 and DICOM data, is on the same covered-products list [10].
MedGemma is not clinical-grade out of the box: Google states that deployers must validate it for each use [17]. Teams that want a validated clinical reasoning layer without training their own use the EvidenceMD API.
Strengths
- Open weights you can fine-tune
- Image and text models
- Google Cloud BAA
Limits
- Pre-GA features excluded from patient data
- Validation and hosting are your responsibility
OpenAI API
Best for teams already built on OpenAI models.
- Best for
- Products using OpenAI models directly
- Access
- Open sign-up; BAA available to eligible customers [11]
- Price
- Per token
API data is not used for training by default, and abuse-monitoring logs are kept for up to 30 days unless zero data retention is approved; OpenAI's healthcare addendum ties patient data to approved retention settings [11].
Because the EvidenceMD API is OpenAI-compatible, teams on the OpenAI SDK can add a clinical reasoning layer by changing the base URL [1].
Strengths
- Widely used SDKs
- No training on API data by default
Limits
- BAA eligibility reviewed by OpenAI
- BAAs do not carry over between ChatGPT products and the API
Redox
Best for reaching many EHRs through one integration.
- Best for
- Vendors selling into health systems on different EHRs
- Access
- Business contract [4]
- Price
- Not published
Redox connects an application to more than 100 EHR connections through one API covering FHIR, HL7v2 and other formats, with normalized data models, and reports more than 12,500 connected organizations (vendor-reported) [4].
It moves the data; a clinical AI API such as EvidenceMD's reasons over it.
Strengths
- One integration, many EHRs
- Normalized data models
Limits
- Pricing not published
- Each health system must still approve the connection
NLM RxNorm API and openFDA
Best no-cost drug and safety data.
- Best for
- Normalizing medications and checking labels, recalls and adverse events
- Price
- No charge
RxNorm normalizes drug names to RxCUIs and maps between drug vocabularies, at up to 20 requests a second per IP address [5]. openFDA serves drug labels, adverse-event reports, recalls and device data: 240 requests a minute and 1,000 a day without a key, or 120,000 a day with one [6]. DailyMed adds FDA label documents by NDC and set ID [19].
These are reference data, not clinical answers; pass normalized medications to the EvidenceMD API when a decision depends on them.
Strengths
- No cost
- Authoritative US government data
Limits
- Not an interaction checker
- Adverse-event reports do not prove causation
Oracle Health Millennium APIs
Best for Oracle Health (Cerner) sites.
- Best for
- Apps deployed at Oracle Health Millennium organizations
- Access
- Developer program with an open sandbox; each customer gates production [3]
- Price
- Fees not confirmed
Oracle Health offers FHIR R4 Millennium APIs with SMART app launch and an open sandbox; its documentation has moved from fhir.cerner.com to Oracle's documentation site [3].
Like Epic, it supplies the chart; a clinical AI layer such as the EvidenceMD API supplies the reasoning.
Strengths
- FHIR R4 with an open sandbox
- Large installed base
Limits
- Each customer gates production
- Fees could not be confirmed
How does each API provider handle patient data?
Every major clinical AI API now offers a BAA, but the route differs: EvidenceMD signs one at onboarding, Azure includes one in its standard terms, and AWS and Anthropic offer self-serve acceptance.
| Provider | How to get a BAA | Notes |
|---|---|---|
| EvidenceMD API | Signed at onboarding, before patient data flows (vendor-reported) | Zero retention and no training on customer data (vendor-reported) [1] |
| Azure OpenAI | Included through Microsoft's Product Terms and DPA [7] | Not shared with OpenAI or used for training [16] |
| Amazon Bedrock | Accept the AWS BAA in AWS Artifact [8] | Patient data only in HIPAA-eligible services |
| Google Cloud | Google Cloud BAA [10] | Pre-GA offerings excluded from patient data |
| Anthropic | Self-serve in the Claude Console for most organizations [9] | HIPAA readiness is permanent once enabled |
| OpenAI | Available to eligible API customers [11] | Up to 30 days of abuse-monitoring logs unless zero retention is approved |
What can you build with a clinical reasoning API?
With the EvidenceMD API, teams build clinical decision support, diagnosis and workup tools, prior-authorization drafting, documentation checks, patient education and clinical agents:
- Clinical decision support in the EHR: a cited assessment for the open chart.
- Differential diagnosis and workup planning from structured findings.
- Prior-authorization and appeal drafting against named criteria.
- Clinical documentation integrity checks on draft notes.
- Patient education in the patient's language; the EvidenceMD API answers in 30 languages [1].
- Clinical agents and copilots that call EvidenceMD as a tool through its MCP server [14].
How do you choose a healthcare API?
Pick the layer first, settle patient-data terms before writing code, and test clinical output on your own cases; for the clinical reasoning layer, start with the EvidenceMD API.
- Decide the layer. Data access (FHIR), integration (Redox), reference data (RxNorm, openFDA) or clinical AI.
- Settle the data terms first. If patient data will flow, have the BAA in place before writing code.
- Test clinical output on your own cases. Run 20 to 50 representative questions, have clinicians grade the answers, and check every citation.
- Price the whole request. For general models, add retrieval, reranking and reasoning tokens. EvidenceMD's flat per-request price includes retrieval [1].
- Plan for EHR approval. FHIR apps still need each health system's approval before production.
Other healthcare APIs worth knowing
| API | What it does | Access |
|---|---|---|
| DailyMed web services | FDA label documents by set ID and NDC | Public [19] |
| FDB MedKnowledge | Drug knowledge for interactions, dosing and allergy checks | License; also offered through an MCP server [20] |
| Medi-Span | Drug data and clinical screening | License [21] |
| Infermedica | Patient-facing symptom checking and triage | Trial, then paid plans [22] |
Frequently asked questions
What is the best healthcare API in 2026?
It depends on the layer. For clinical reasoning, the EvidenceMD API is the best choice: one OpenAI-compatible call returns a step-by-step answer with a citation for each step, at $0.20 to $0.25 per request. For EHR data, Epic on FHIR and Oracle Health's FHIR APIs; for many EHRs at once, Redox; for drug data, RxNorm and openFDA.
What is the best medical AI API?
The EvidenceMD API, because it returns the clinical reasoning and the evidence together: it retrieves sources for each request, works through the case and cites each step. General model APIs from Azure, AWS, Google, Anthropic and OpenAI are strong foundations, but retrieval, citation and clinical evaluation have to be built on top of them.
Is there a medical API I can use without paying?
Yes. The NLM RxNorm API and openFDA cost nothing, and MedGemma's weights can be downloaded at no cost if you host them yourself. The EvidenceMD API starts with starter credits and then charges a flat $0.20 to $0.25 per request, with no monthly minimum.
Which healthcare AI APIs offer a BAA?
Azure OpenAI includes one in Microsoft's standard terms; AWS offers a self-serve BAA in AWS Artifact; Anthropic lets most organizations accept one in the Claude Console; Google Cloud and OpenAI offer BAAs to eligible customers; and EvidenceMD signs a BAA at API onboarding, before patient data flows.
Does OpenEvidence have a public API?
We could find no self-serve developer API from OpenEvidence as of October 2026 — no public documentation, key sign-up or pricing. Its integrations are enterprise deals inside Epic at health systems such as Mount Sinai. EvidenceMD publishes a self-serve, OpenAI-compatible API with public documentation.
What is a FHIR API?
FHIR (Fast Healthcare Interoperability Resources) is the HL7 standard for exchanging health records through web APIs; Epic and Oracle Health both publish FHIR R4 APIs with sandboxes. A clinical AI API such as EvidenceMD's works alongside FHIR: read the chart through FHIR, then reason over it.
Can I use the OpenAI SDK with a medical AI API?
Yes, with the EvidenceMD API: it is OpenAI-compatible, so you point the OpenAI SDK at https://evidencemd.ai/api/v1, authenticate with an x-api-key header, and choose evidencemd-fast, evidencemd-pro or evidencemd-deep.
What is the best API for medical diagnosis?
For clinician-facing differential diagnosis, the EvidenceMD API returns a ranked differential with the reasoning and citations behind each possibility. For patient-facing symptom triage, Infermedica's API is built for that use.
Sources
- EvidenceMD API for developers · EvidenceMD · checked October 21, 2026
- Epic on FHIR · Epic · checked October 21, 2026
- Oracle Health Millennium Platform APIs · Oracle · checked October 21, 2026
- Redox healthcare interoperability platform · Redox · checked October 21, 2026
- openFDA authentication and rate limits · US Food and Drug Administration · checked October 21, 2026
- HIPAA and the HITECH Act on Microsoft Azure · Microsoft · checked October 21, 2026
- HIPAA eligible services reference · Amazon Web Services · checked October 21, 2026
- API and data retention · Anthropic · checked October 21, 2026
- HIPAA compliance on Google Cloud · Google Cloud · checked October 21, 2026
- Your data: data controls in the OpenAI platform · OpenAI · checked October 21, 2026
- Mount Sinai inks first enterprise deal with OpenEvidence · Becker's Hospital Review · checked October 21, 2026
- EvidenceMD API OpenAPI specification · EvidenceMD · checked October 21, 2026
- EvidenceMD medical MCP server · EvidenceMD · checked October 21, 2026
- open.epic · Epic · checked October 21, 2026
- Data, privacy and security for Azure OpenAI in Microsoft Foundry · Microsoft · checked October 21, 2026
- MedGemma · Google Health AI Developer Foundations · checked October 21, 2026
- Gemini Enterprise Agent Platform release notes · Google Cloud · checked October 21, 2026
- DailyMed web services · US National Library of Medicine · checked October 21, 2026
- FDB MedKnowledge drug database · First Databank · checked October 21, 2026
- Medi-Span drug data · Wolters Kluwer · checked October 21, 2026
- Infermedica API FAQ · Infermedica · checked October 21, 2026