AI Agents Compared: Claude vs ChatGPT vs Gemini vs Grok (2026)

Every major AI lab now sells agents, not just chatbots. Anthropic, OpenAI, Google and xAI each ship an agent that works inside its consumer app, a coding agent, a developer SDK, and some way for a business to build its own custom agents. The products overlap a lot, the names change every few months, and the marketing makes them sound more alike than they are.

This guide compares what agent capabilities Claude, ChatGPT, Gemini and Grok actually offer as of October 2026, layer by layer, and ends with a verdict for each common use case. Every product named here was checked against vendor documentation or launch coverage this month. Where a vendor's claim could not be confirmed, we say so.

What can AI agents do?

AI agents can take a goal, break it into steps, use tools to carry those steps out, and keep going until the job is done, without a person prompting each step. In practice that means an agent can research a topic across dozens of web pages and write up the findings, work through your inbox and draft replies, fill in forms and operate websites that have no API, write and test code across a whole repository, or run a recurring report every Monday morning.

The difference from a chatbot is autonomy and tools. A chatbot answers a message. An agent has access to a browser, a file system, a terminal, or connected apps like Gmail and Slack, and it decides which of those to use next. The four vendors below all give their agents roughly the same toolbox. What separates them is where the agent runs, who it is built for, and how much control you get over it.

For a business, the useful question is not "which AI has agents" but "which agent layer do I need". Most businesses need one of three things: a ready-made agent that staff can hand tasks to, a coding agent that builds and maintains software, or a platform for building a custom agent that runs a specific workflow such as lead follow-up, content production or customer support.

Claude, ChatGPT, Gemini and Grok agents at a glance

The short version: Claude leads on coding agents and developer-built agents, ChatGPT has the widest range of ready-made agents for non-technical teams, Gemini is the strongest choice for businesses that live in Google Workspace or Google Cloud, and Grok is the newest entrant, with a capable cloud agent in early beta and a much thinner business story.

All four now have an always-on or cloud-hosted agent for consumers, a coding agent, and an API with built-in tools. Only three of the four, Anthropic, OpenAI and Google, offer a mature hosted runtime for developers to deploy custom agents, and only Google and OpenAI offer a no-code agent builder aimed at business teams.

Gemini agents: what Google offers

Google's agent lineup is the broadest of the four, and the most confusing, because it spans the consumer Gemini app, Google Workspace, Google Cloud and a separate developer brand called Antigravity. Here is how the pieces fit.

Gemini Spark, the consumer Gemini agent

Gemini Spark is Google's personal AI agent, announced at Google I/O on 19 May 2026. It runs on Google Cloud virtual machines rather than on your device, so it keeps working when your laptop is closed. According to Google and launch coverage, Spark can manage your inbox and calendar, carry out multi-step tasks on the web through Chrome, and work with Gmail, Docs and Slides out of the box, with MCP connections to outside services such as Canva, OpenTable and Instacart. You can even email it tasks through a dedicated Gmail address. It asks for consent before high-impact actions like spending money or sending email. In June 2026 Google added Spark to the Gemini app for macOS, where it can organize local folders and build documents from local files.

Spark is only available on Google AI Ultra, Google's top consumer plan, and it launched in the US first. If you are on a cheaper Gemini plan, you get Deep Research and connected apps, but not the autonomous agent.

Gems and skills, the custom assistant layer

Gems were Google's answer to custom GPTs: saved assistants with their own instructions and files. On 30 September 2026 Google announced that skills, reusable instructions you can stack within a single task, will replace Gems, and that existing Gems will be migrated to skills automatically. If you are setting up a new custom assistant in Gemini today, build it as a skill.

Google's coding agents: Antigravity and Jules

Google consolidated its coding tools under the Antigravity brand in 2026. Antigravity 2.0, launched at I/O, is a desktop app for running several coding agents in parallel, with subagents and scheduled background tasks. The Antigravity CLI replaces Gemini CLI, which Google asked users to migrate away from in mid-2026, and the Antigravity SDK gives developers the same agent harness to host on their own infrastructure. Jules, Google's asynchronous coding agent, still works the way it did at launch: you assign it a task against a GitHub repository and it opens a pull request for review.

Gemini API managed agents

For developers, Google added managed agents to the Gemini API at I/O 2026. Google says a single API call creates an agent that can reason, use tools and run code in an isolated Linux environment that persists across follow-up calls. It is available through the Interactions API and Google AI Studio, and Google says it runs on Gemini 3.5 Flash.

Gemini Enterprise Agent Platform

The business layer is the Gemini Enterprise Agent Platform, announced at Google Cloud Next on 22 April 2026. It replaces Vertex AI as Google Cloud's agent-building home and covers the whole range of builders. Agent Designer, inside the Gemini Enterprise app, lets employees create agents with no code. Agent Studio is a low-code environment. The Agent Development Kit, or ADK, is the code framework for multi-agent systems, and Agent Runtime hosts long-running agents. Google also includes governance tools such as agent identity, an agent registry and a policy gateway, plus an Agent Gallery of prebuilt and partner agents.

One detail that matters for anyone choosing between vendors: the platform's Model Garden includes Anthropic's Claude models alongside Gemini, and xAI says Grok 4.6 is available there too. A business that standardizes on Google Cloud does not have to standardize on Gemini models.

AI agent builders that work with Gemini

If you want a list of AI agent builders that work with Gemini, start with Google's own tools and then add the third-party platforms most builders on this site already use.

From Google, there are five options, sorted from no-code to full code. First, Agent Designer in Gemini Enterprise, for business users who want to describe a workflow and get an agent. Second, Agent Studio in the Gemini Enterprise Agent Platform, for low-code builders. Third, Google AI Studio, which now supports managed agents and can export a project into Antigravity. Fourth, the Agent Development Kit, Google's open framework for building multi-agent systems in code. Fifth, the Antigravity SDK, for developers who want Google's own agent harness running on their infrastructure.

Outside Google, the automation platforms n8n, Make and Zapier all offer Gemini integrations, so you can drop a Gemini model into a visual workflow next to your CRM, inbox and spreadsheets. Code frameworks such as LangGraph and CrewAI also support Gemini models. Most voice agent platforms let you choose a Google model too, though support varies by platform and changes often, so check the current model list before you build.

For most small businesses and agencies, the practical choice is between Agent Designer, if you already pay for Gemini Enterprise, and n8n or Make with a Gemini model, if you want the agent to connect to tools outside Google's ecosystem.

Grok agents: what xAI offers

xAI's agent lineup arrived late but is moving quickly. The most important product is Grok Bot, and the most important caveat is that almost all of it is still in beta.

Grok Bot, the xAI agent

Grok Bot entered early beta on 11 August 2026. Each bot gets its own cloud computer with a browser, file system, terminal and memory, signs in to the apps you use, and keeps working when your own computer is off. Bots can connect to services through built-in connectors such as Gmail and Google Calendar, and through custom remote MCP servers, and several bots can coordinate with each other. xAI calls them teammates.

Access is the messy part. Launch coverage disagrees on exactly which plans include Grok Bot, but it was available on xAI's top SuperGrok Heavy tier and, through a bundling arrangement, on some Cursor plans. Business access started on a waitlist, and xAI has since published a post on Grok Bot for Enterprise. If you are evaluating it, check xAI's current plan page rather than relying on launch reviews.

Grok custom agents

Grok's custom agents feature, launched in March 2026 according to third-party coverage, lets you set up to four agents in a "Your Agents" screen, each with its own personality, focus area and instructions. These are closer to Gems or custom GPTs than to Grok Bot: they shape how Grok answers, but they do not run tasks on their own. The same coverage reports that Grok's custom instructions limit was cut to 4,000 characters in that update, which makes it hard to pack a detailed business workflow into one.

Grok Build, the coding agent

Grok Build is xAI's terminal coding agent, launched in early beta in May 2026. It plans multi-step work, edits files, runs commands, offers a plan mode for reviewing changes before they are made, and can run several specialized agents in parallel. It runs on xAI's coding model, grok-build-0.1, which xAI's API documentation lists at $1 per million input tokens and $2 per million output tokens.

Building on the xAI API

Developers can build agents directly on the xAI API. It supports a Responses API, function calling for your own tools, and built-in server-side tools for web search, X search, a Python code interpreter, image generation and search over your uploaded document collections. The API is compatible with the OpenAI SDK, which makes it easy to swap Grok into an existing agent. xAI also offers a multi-agent version of Grok 4.20 that runs several agents internally before answering. What xAI does not offer yet is a hosted agent runtime or a visual agent builder, so a business building a custom Grok agent is writing and hosting the orchestration itself, or using a third-party platform. Grok models are also available through Amazon Bedrock and Google's Gemini Enterprise Agent Platform, according to xAI.

The one area where Grok is clearly different is X. Native X search makes it the obvious choice for agents that monitor social conversation, track brand mentions or summarize breaking news from X posts.

ChatGPT and Claude agents, briefly

We compare these two in depth in our Claude vs ChatGPT guide, so here is the short version for context.

OpenAI's consumer agent is ChatGPT Work, launched in July 2026, which replaced the older ChatGPT agent mode and Operator. It works across your apps and files for hours at a time and can run scheduled tasks. At DevDay on 29 September 2026 OpenAI announced Dots, always-on agents that each get their own cloud computer, rolling out to Pro and business plans. For teams, workspace agents are the successor to custom GPTs and let a business turn a recurring workflow into a shared agent without code. Developers get Codex for coding, the Agents SDK, and the Agents API, which entered public beta in September 2026 and runs the Codex harness as a managed service. OpenAI's visual Agent Builder is being retired on 30 November 2026.

Anthropic's consumer agent is Cowork, which is being merged into the main Claude app, plus Claude in Chrome, a browser agent that became generally available on paid plans in August 2026. Claude Code is the coding agent and runs in the terminal, IDEs, the desktop app and cloud sessions on the web. Developers build custom agents with the Claude Agent SDK and can host them on Claude Managed Agents, which is in beta and which Anthropic lists at $0.08 per session-hour on top of token costs. Skills and MCP, which Anthropic created, are how most Claude agents get their capabilities.

Can a business build custom agents on each platform?

Yes on all four, but the effort varies a lot.

On Claude, a business builds custom agents in code with the Claude Agent SDK, hosts them on Managed Agents or its own servers, and packages repeatable workflows as skills. There is no first-party drag-and-drop builder, so most non-developers use Claude through n8n, Make or Zapier instead.

On ChatGPT, a business has the most options without code: workspace agents for team workflows, ChatGPT Work for one-off long tasks, and Dots for always-on work. Developers use the Agents SDK or Agents API.

On Gemini, a business on Google Workspace or Google Cloud has a full ladder from no-code Agent Designer to the ADK, with enterprise governance built in. This is the most complete business agent platform of the four, and the most expensive to set up properly.

On Grok, a business can build on the API or wait for Grok Bot for Enterprise. There is no hosted runtime or no-code builder yet, so today it is the hardest of the four for a non-technical team to build on.

Verdict: which AI agent to use for each job

For coding agents, pick Claude Code or Codex. Both are mature and many developers pay for both. Antigravity is a credible third choice for teams on Google Cloud. Grok Build is still an early beta.

For agents that a marketing or SEO agency builds for clients, pick Claude with the Agent SDK and skills, or Claude inside n8n or Make. It is a common pattern among the agency strategies we catalogue, because Claude follows long brand and style instructions faithfully and writes copy that needs less editing.

For a non-technical team that wants agents without code, pick ChatGPT. Workspace agents and ChatGPT Work are the most complete ready-made options, and most staff already know the interface.

For a business that runs on Google Workspace, pick Gemini. Spark and the Gemini Enterprise agents work natively with Gmail, Calendar, Docs and Drive, and Agent Designer lets staff build their own agents without leaving Google's admin controls.

For a local business that wants an agent to handle admin, such as inbox triage, appointment follow-up and review responses, any of ChatGPT Work, Claude or Gemini Spark will do the job; pick the one that connects to the apps you already use. For phone calls specifically, a dedicated voice agent platform is still the better tool than any of these four.

For monitoring X, social listening or news-driven research, pick Grok. Native X search is a real advantage no other vendor can match.

For long-running research and reporting, ChatGPT Work, Claude and Gemini's Deep Research are all strong. Grok is useful when the research depends on real-time X posts.

Frequently Asked Questions