What Is Claude AI? Anthropic's Assistant, Explained

Claude is the conversational AI assistant built by Anthropic, an AI safety company founded by former OpenAI researchers. Like other modern chatbots, you talk to it in plain language and it writes, summarizes, codes and reasons through problems for you. Claude’s reputation is for being especially strong at long-form writing, careful reasoning and coding — and for an unusually heavy focus on safety. If the underlying technology is new to you, our explainer on how AI chatbots work covers the fundamentals.

Where Claude comes from

Anthropic was founded in 2021 by a group of researchers who left OpenAI, led by siblings Dario and Daniela Amodei. The company positions itself around AI safety: the idea that frontier AI systems should be built to be reliable, steerable and aligned with human intentions. Claude is its flagship product, and the assistant is often described as being named after Claude Shannon, a pioneer of information theory.

You can use Claude through the claude.ai website and apps, through a developer API, and through tools like Claude Code for programming in the terminal.

What makes Claude different

A few things set Claude apart from rival assistants:

A safety-first design philosophy. Anthropic trains Claude with a method it calls Constitutional AI, steering the model toward responses that are helpful, honest and harmless using a written set of principles rather than human feedback alone.
Strength in writing, coding and reasoning. Claude is widely favored for long-form drafting, nuanced editing, careful step-by-step reasoning and software development.
A large context window. Claude can take in very long documents — think lengthy reports, contracts or codebases — and work across all of it in a single conversation.
Useful building blocks. Features like Artifacts (a side panel for code, documents and apps it generates) and Claude Code make it practical for real work, not just chat.

The Claude model family

Rather than one model, Claude comes as a lineup tiered by capability and speed:

Opus — the most capable tier, built for the hardest reasoning, research and coding tasks.
Sonnet — the balanced, everyday workhorse, fast enough for interactive use while still highly capable.
Haiku — the fastest and most lightweight tier, tuned for quick, high-volume tasks.

Anthropic refreshes this lineup regularly with new versions, so the specific model names and numbers change over time. The tier names — Opus, Sonnet, Haiku — are the durable part.

How it compares to ChatGPT and Grok

All the major assistants do broadly the same things, and the leaderboard shifts every time someone ships a new model. In practice:

Claude (Anthropic) is the go-to for long-form writing, coding and careful reasoning, with a safety-focused design.
ChatGPT (OpenAI) has the largest ecosystem and the broadest feature set.
Gemini (Google) is woven into Google’s products and search.
Grok (xAI) leans on real-time data from X and a looser personality — see our explainer on what Grok is.

The “best” one really depends on the task. For a closer side-by-side, see our full ChatGPT vs Claude vs Grok comparison. When accuracy matters, it’s worth checking an answer across two assistants rather than trusting any single one.

Is Claude free?

Yes — there’s a free tier on claude.ai with usage limits. Paid plans like Claude Pro raise those limits and unlock access to the more capable models, and developers pay per-use through the API. Exact limits and pricing change often, so check Anthropic for current details.

Getting the most out of Claude

Picking the right assistant is only half the battle; the bigger wins come from using purpose-built tools layered on top of these models. If you want software tuned for a specific job — drafting, editing, SEO content — see our roundup of the best AI writing tools.

FAQ

Who makes Claude AI?

Claude is made by Anthropic, an AI safety company founded in 2021 by former OpenAI researchers, including siblings Dario and Daniela Amodei.

Is Claude better than ChatGPT?

Neither is universally “better.” Claude is widely favored for long-form writing, coding and careful reasoning, while ChatGPT has a broader ecosystem and feature set. The gap shifts with every new model release, so the best choice depends on your task.

Is Claude free to use?

Yes. There’s a free tier on claude.ai with usage limits, plus paid plans like Claude Pro that raise the limits and unlock the most capable models. Developers can also pay per use through the API.

What are Opus, Sonnet and Haiku?

They’re the tiers of the Claude model family: Opus is the most capable, Sonnet is the balanced everyday option, and Haiku is the fastest and most lightweight. Anthropic updates the specific versions regularly.

The AI field moves fast and model capabilities change frequently. This explainer reflects the current landscape and is reviewed periodically.