Is the OpenAI Assistants API deprecated?

Not formally deprecated at the time of writing, but it's been eclipsed. OpenAI has shifted its building blocks: the Responses API for lower-level inference with tool use, and ChatGPT Workspace Agents for productized, team-owned autonomous workflows. Most teams that would have built on Assistants API in 2024–2025 should now use Workspace Agents (if you have ChatGPT Business/Enterprise) or the Responses API (if you're building a custom product).

What's the difference between Assistants API and Workspace Agents?

Assistants API is a developer-facing API for building your own assistant-style product from scratch — you host the UI, manage threads, handle tool execution. Workspace Agents is a finished product that runs inside ChatGPT Business or Enterprise — an admin configures it, team members invoke it, OpenAI manages execution. If your goal is 'give our team a working AI agent,' Workspace Agents is the faster, cheaper path. Assistants API only makes sense if you're building a product to sell to others.

Can I migrate from Assistants API to Workspace Agents?

If the assistant was internal-facing (used by your own team), yes — and you probably should. The prompt, the tool specs, and the grounding documents all transfer. The main work is re-wiring tool calls to native connectors (HubSpot, Drive, Slack, etc. are first-class in Workspace Agents). Typical migration is 1–2 days for a straightforward assistant.

Does Assistants API support connectors like HubSpot or Slack?

Not natively the way Workspace Agents do. On Assistants API you write custom function tools that call HubSpot or Slack via their APIs yourself. On Workspace Agents, your admin authorizes the connector once at the workspace level and every agent on that workspace can read/write to it, with permission inheritance from the source tool.

What about pricing — is Assistants API cheaper?

Per-token, the underlying API is roughly comparable. In practice, Workspace Agents are cheaper for most teams because you're not paying engineers to build the UI, handle thread state, or maintain tool integrations. If you have one agent and no dev team, Workspace Agents is usually the lower total cost of ownership. If you have ten agents and a dev team building a product, the Assistants API or Responses API can be cheaper at scale.

Should I use the Responses API instead of Assistants API in 2026?

If you're building from scratch in 2026, yes — OpenAI is steering new development toward the Responses API as the lower-level primitive. It's designed around the stateless, tool-calling pattern that most modern agents use. Assistants API still works, but new features and OpenAI's own guidance point to Responses. For team-facing internal agents, skip both and use Workspace Agents.

What if I'm already on Assistants API in production?

Don't panic — it still works. Review whether the workload is internal (your team) or external (you ship the assistant to customers). Internal: migrate to Workspace Agents within a quarter or two. External: plan a migration to the Responses API on your next major version; the semantics are close enough that the porting work is mostly mechanical.

Does the Assistants API support code execution and file search?

Yes — code_interpreter and file_search are first-party tools on Assistants API, and they're what most teams picked it for. Workspace Agents includes these same capabilities (plus connectors), so migrating doesn't lose functionality. Building on top of Responses API, you wire these tools yourself or via the OpenAI Agent Kit.

Guide · Updated April 24, 2026

OpenAI Assistants API: What It Is, What Replaced It, and When to Pick It in 2026

If you landed here searching for the OpenAI Assistants API, you’re probably evaluating how to build an AI agent on top of OpenAI’s stack. The landscape changed materially between 2024 and 2026. This guide covers what the Assistants API actually is, what OpenAI has launched since, and — most importantly — the three-question decision tree for whether the Assistants API is still the right call for your use case.

What the Assistants API actually is

The OpenAI Assistants API is a stateful, higher-level developer API that abstracts away the plumbing of building an AI assistant. You create an assistant (the prompt, tools, files) once, then route user messages into threads that persist across turns. OpenAI handles message history, tool invocation, and the scheduling of when to call the model vs. when to yield back to your code.

Three built-in tools make it useful out of the box: code_interpreter (sandboxed Python), file_search (RAG over uploaded documents), and function calling (your own tool definitions). In 2024 this was the fastest way to build a bespoke AI assistant for your product.

It’s still available. OpenAI has not formally deprecated it. But the center of gravity has moved.

What replaced Assistants API — and for whom

Workspace Agents — for internal team use on ChatGPT Business or Enterprise

If the assistant is for your own team (sales, support, ops, finance), ChatGPT Workspace Agentsis the upgrade path. It’s productized: no UI to build, no thread management, native connectors for HubSpot/Slack/Drive/etc., admin controls, and OpenAI handles execution. Launched April 22, 2026.

Responses API — for custom customer-facing products

If you’re building an AI assistant as part of a product you sell, the Responses API is OpenAI’s newer, lower-level primitive. It’s stateless by design, built around modern tool-calling patterns, and plays nicely with the OpenAI Agent Kit for orchestrating multi-step flows.

Assistants API — still valid for legacy workloads

If you have an Assistants API integration running in production, keep it. New projects should default elsewhere.

A three-question decision tree

Skip the API documentation rabbit hole. Ask three questions:

Who is the assistant for? Your own team → Workspace Agents. Your customers → Responses API.
Do you have ChatGPT Business or Enterprise?If yes and the answer to Q1 was "own team," stop here — use Workspace Agents. You’ll ship in a week, not a quarter.
Do you have a dev team committed to maintaining this?If no — don’t pick Assistants API or Responses API. Workspace Agents is the no-code route.

The practical upshot: over 90% of the teams I talk to who came in asking about the Assistants API end up on Workspace Agents. It’s usually what they actually wanted; they just hadn’t seen it launch yet.

Feature comparison

Capability	Assistants API	Workspace Agents	Responses API
Built-in UI	No	Yes — inside ChatGPT	No
Thread state management	Yes (hosted)	Yes	No (stateless)
Native connectors	No — write your own	Yes — HubSpot, Slack, Drive, etc.	No
Admin controls	No	Yes — at workspace level	No
Code execution	Yes	Yes	Via Agent Kit
File search / RAG	Yes	Yes	Via Agent Kit
Team ownership	No	Yes	No
Scheduled triggers	No	Yes	Build it yourself
Best for	Legacy integrations	Internal team agents	Custom product dev

Migrating from Assistants API to Workspace Agents

For internal-facing assistants, the migration is largely mechanical. The prompt text, the tool specifications, and the grounding documents all port over. The rewiring work is:

Replace custom-coded HubSpot/Slack/Drive tool calls with native Workspace Agent connectors (one-time admin authorization per connector).
Move uploaded files from the Assistants API file store into the agent's grounding documents inside ChatGPT.
Rewrite the few function calls that don't map cleanly as Actions (OpenAPI-defined custom tools).
Set up per-agent memory scope and admin controls — concepts the Assistants API doesn't have.
Hand off ownership to a named team member and retire the Assistants API endpoint.

A typical migration takes 1–2 days for a single assistant. If you’re on ChatGPT Business or Enterprise and want help, this is exactly the kind of scope I ship in a week.

When Assistants API is still the right choice

Honestly? Rarely, in 2026. The two thin cases are:

You have existing Assistants API code in production and the migration cost outweighs the gain — keep shipping, plan the port for a major release.
You're building a specialized assistant-style product where Workspace Agents' team-scoped model doesn't fit and you want OpenAI to manage thread state rather than rebuilding it on the Responses API.

Beyond that — start on the newer primitives.

Questions

Moving off Assistants API and onto Workspace Agents?

20-min call. I'll tell you whether your existing assistant belongs on Workspace Agents or the Responses API, and how long the port actually takes on your stack.

Book a 20-min intro call Or send a note