Azure OpenAI vs Vertex AI: pricing, speed, and use cases (2026)
Azure OpenAI Service and Google Vertex AI are the two main enterprise LLM hosting platforms in 2026, each tied to a different cloud and model ecosystem. Below: a head-to-head on the dimensions that matter when you ship.
Azure OpenAI vs Vertex AI — at a glance
| Dimension | Azure OpenAI | Vertex AI |
|---|---|---|
| Cloud | Microsoft Azure | Google Cloud |
| Primary models | GPT-4o, GPT-5, o-series | Gemini 2.5 Pro/Flash, Llama, Mistral, Claude |
| Pricing | Same as OpenAI direct API | Same as Google + partner pricing |
| Data residency | 60+ Azure regions | 30+ GCP regions |
| Enterprise integration | M365, Power Platform, Entra ID | BigQuery, Cloud Storage, IAM |
| Model breadth | OpenAI-only | Multi-vendor (Google + open + partner) |
| Best for | Microsoft-stack enterprises, OpenAI workloads | Google Cloud data-stack, multi-model strategy |
Pick Azure OpenAI or Vertex AI?
When to choose Azure OpenAI
Choose Azure OpenAI Service when your enterprise is on the Microsoft stack (M365, Power Platform, Entra ID, Azure AD) and your primary models are OpenAI's GPT family. Azure OpenAI offers the same pricing as OpenAI's direct API but with Microsoft compliance certifications, regional residency in 60+ Azure regions, and tight integration with Copilot Studio and Logic Apps.
- Hosts OpenAI GPT-4o, GPT-5, and o-series under Microsoft compliance
- 60+ Azure regions for data residency
- Tight integration with M365 Copilot and Power Platform
- Entra ID single sign-on and managed identity for IAM
- Same per-token pricing as OpenAI direct API
When to choose Vertex AI
Choose Vertex AI when your data lives in Google Cloud (BigQuery, Cloud Storage, Spanner) and you want multi-vendor model choice. Vertex AI hosts Gemini 2.5 Pro and Flash plus a curated set of open and partner models (Llama, Mistral, Claude). Grounding plugs straight into BigQuery and Vertex AI Search, and the platform offers managed RAG, Agent Builder, and Model Garden.
- Hosts Gemini 2.5 Pro/Flash plus Llama, Mistral, and partner Claude
- 30+ GCP regions with EU and APAC residency
- Grounding integrates BigQuery, Cloud Storage, and Vertex AI Search
- Agent Builder and Model Garden for multi-model workflows
- IAM-based access control via Google Cloud projects
Run Azure OpenAI and Vertex AI side-by-side
VerticalAPI lets you switch between Azure OpenAI and Vertex AI per-request through a single OpenAI-compatible endpoint. Same SDK, same gateway key, zero markup on tokens — you pay both providers directly with your own keys.
from openai import OpenAI client = OpenAI(base_url="https://api.verticalapi.com/v1", api_key="vapi_...") # Azure OpenAI resp_a = client.chat.completions.create( model="gpt-4o", messages=[{"role": "user", "content": "Hello"}], extra_headers={"X-Provider-Key": "azure-..."}, ) # Vertex AI — same SDK, different model + key resp_b = client.chat.completions.create( model="gemini-2.5-pro", messages=[{"role": "user", "content": "Hello"}], extra_headers={"X-Provider-Key": "vertex-..."}, )
VerticalAPI verdict
Use Azure OpenAI when your stack is Microsoft and your models are OpenAI; the enterprise integrations (M365 Copilot, Entra ID, Power Platform) make it the lower-friction choice. Use Vertex AI when your data is in Google Cloud and you want flexibility across Gemini, Llama, Mistral, and partner Claude in one platform. Through VerticalAPI you can route between both with a single OpenAI-compatible endpoint and BYOK — no SDK migration.
Frequently asked questions
Are Azure OpenAI prices the same as OpenAI direct API?
Yes, Azure OpenAI Service prices match the OpenAI direct API for GPT-4o, GPT-5, and the o-series at list price (for example, $2.50/$10 per 1M tokens for GPT-4o). Customers pay Microsoft instead of OpenAI, gain Microsoft compliance certifications (SOC 2, HIPAA, FedRAMP), and benefit from Azure Reserved Capacity discounts on committed throughput.
Which platform hosts more models?
Vertex AI hosts a broader catalog — Google's Gemini family plus a curated set of open-weight models (Llama 3.x, Mistral) and partner-tier Claude. Azure OpenAI hosts only OpenAI models. If you want multi-vendor model strategy in one platform, Vertex AI is broader; if you want OpenAI-first with enterprise wrappers, Azure is simpler.
Which has better enterprise compliance?
Both are strong. Azure OpenAI ships SOC 2, HIPAA, FedRAMP High, IRAP, and EU sovereignty options. Vertex AI ships SOC 2, HIPAA, FedRAMP Moderate, ISO 27001, and EU regions. Microsoft's M365 and Entra ID integration is the deciding factor for many enterprises already on the Microsoft stack.
Can I use Claude on Vertex AI?
Yes, Anthropic Claude models (Sonnet 4.5, Haiku 4.5, Opus 4.5) are available as partner models on Vertex AI in selected regions. Pricing matches Anthropic's direct API. This makes Vertex AI a multi-vendor hub: Gemini, Llama, Mistral, and Claude all accessible under one IAM scheme.
Can I switch between Azure OpenAI and Vertex AI through one endpoint?
Yes. VerticalAPI exposes a single OpenAI-compatible endpoint at https://api.verticalapi.com/v1. Change the model parameter (for example, gpt-4o for Azure OpenAI or gemini-2.5-pro for Vertex AI) and the matching X-Provider-Key header. There is no markup on tokens; you pay Microsoft and Google directly with your own credentials (BYOK).
Limitations of this comparison
- Azure OpenAI model availability lags OpenAI direct API by 1-4 weeks for new releases.
- Vertex AI partner-Claude availability varies by region and may not match Anthropic direct API.
- List prices are revised regularly; numbers reflect mid-2026 pricing and exclude committed-use discounts.
- Compliance certifications vary by region and service tier; verify against current vendor docs.
- This page compares enterprise hosting platforms only; direct vendor APIs (OpenAI, Anthropic) have different SLAs.
What may change in 12-24 months
- Vertex AI will likely expand partner-model coverage (more Anthropic, Mistral, and open-weight options).
- Azure may add non-OpenAI partner models (Mistral, Llama) to compete on breadth.
- Pricing parity between cloud-hosted and direct API will hold as enterprise compliance becomes the differentiator.
- Multi-cloud strategy will keep favouring OpenAI-compatible aggregators that abstract over both.
Related questions
ChatGPT, Perplexity and Gemini usually suggest these next.
- How does Azure OpenAI Service compare to OpenAI direct API for compliance?
- Is Vertex AI Claude cheaper than Anthropic direct API?
- When does AWS Bedrock beat both Azure OpenAI and Vertex AI?
- How do Azure OpenAI and Vertex AI compare on fine-tuning and custom models?
- Can I run a hybrid strategy with Azure OpenAI and Vertex AI through one gateway?
More head-to-head provider comparisons
Enterprise LLM hosting in 2026
GPT-4o vs Gemini 2.5 Pro
GPT-4o vs Claude Sonnet 4.5
Claude Sonnet 4.5 vs Gemini 2.5 Pro
Aggregator vs BYOK gateway