OpenAI provides a cloud-based API with an official JavaScript/TypeScript SDK for accessing state-of-the-art language models like GPT-4o. It handles all infrastructure, scaling, and model updates while offering enterprise-grade reliability and sophisticated features like function calling, structured outputs, and streaming. The SDK is designed for production applications where model quality and zero-maintenance deployment are priorities.
Ollama is a local inference runtime that runs open-source LLMs (Llama, Mistral, etc.) directly on your hardware. It exposes an OpenAI-compatible API, allowing JavaScript developers to integrate it using the standard OpenAI SDK or direct HTTP calls. The tool targets developers who need privacy, zero inference costs, offline capability, or full control over model selection and deployment. Both serve JavaScript applications but represent fundamentally different architectural approaches: cloud-first versus local-first AI.
Choose OpenAI if you're building production JavaScript applications where model quality, reliability, and zero-ops deployment matter more than cost-per-request. It's the clear winner for customer-facing products, complex agents requiring function calling, applications needing elastic scaling, or teams without ML infrastructure expertise. The premium you pay buys world-class models, predictable latency, and the ability to focus entirely on JavaScript application logic rather than GPU management. This is the right default for startups, SaaS products, and any scenario where development velocity and consistent behavior outweigh inference costs.
Choose Ollama when privacy, cost control, or offline capability are non-negotiable requirements for your JavaScript project. It dominates in regulated industries (healthcare, finance), high-volume internal tooling where inference costs would be prohibitive, rapid prototyping without API quotas, and any scenario requiring data sovereignty. Accept the operational overhead of managing models and hardware in exchange for zero marginal costs and complete control. For most developers, a hybrid approach works best: Ollama for local development and testing, OpenAI for production deployments where quality and scale justify the expense.