Claude is an AI assistant developed by Anthropic, available through the web, mobile apps, and a developer API. Like ChatGPT, Claude can write, analyze, summarize, answer questions, and write code — but it is built on a distinct approach to AI safety and tends to excel at nuanced reasoning and long-document work. This explainer covers what Claude is, how its model family is organized, and how to get started.

What Makes Claude Different

Claude was created by Anthropic, an AI safety company founded in 2021 by former OpenAI researchers. The central distinction is the training methodology: Anthropic developed an approach called Constitutional AI (CAI) — a process in which the model learns to critique and revise its own responses according to a set of principles drawn from sources such as the UN Declaration of Human Rights. Rather than relying solely on human labelers to flag harmful content, CAI has the model evaluate itself against those principles during training.

In practice, Claude is designed to be helpful, harmless, and honest — and to decline requests that conflict with those principles while explaining why. The training does not make Claude infallible, but it does make its limits more consistent and explainable than many alternatives.

The Claude Model Family

Anthropic organizes Claude into tiers, each offering a different balance of speed, capability, and cost:

Haiku is the fastest and most affordable tier. It handles routine tasks well — summarizing, extracting, classifying — and suits cost-sensitive or high-volume applications.

Sonnet is the mid-tier: more capable than Haiku, but faster and cheaper than Opus. It is Anthropic’s recommended choice for most production tasks, balancing intelligence with response speed. Sonnet 5, the latest version, raised the bar for mid-tier models significantly.

Opus is the most capable publicly available tier. It handles complex reasoning, multi-step coding tasks, and long-horizon analysis. The trade-off is higher cost and somewhat slower output.

Fable is Anthropic’s frontier tier, intended for cutting-edge research and high-stakes applications. Availability can vary depending on regulatory and infrastructure constraints.

Each tier receives version updates (e.g., Sonnet 5, Opus 4.8). Newer versions within a tier are generally more capable; older versions may remain available through a transition period before retirement.

How to Get Started

The easiest entry point is claude.com, Anthropic’s web interface. A free account gives access to Claude’s mid-tier model with a rolling usage limit — enough to evaluate the assistant for everyday tasks without a credit card.

Claude Pro (as of July 2026: $20/month) raises those limits significantly, adds priority access during peak hours, and unlocks the latest and most capable models including Opus. Team and enterprise plans add multi-seat management, usage controls, and additional security features. See the current plans at claude.com/pricing.

Developers can access Claude through Anthropic’s API, where pricing is by token — the unit of text that models process. As of July 2026, API pricing starts at around $1 per million input tokens for Haiku and scales to $5 per million for Opus; see the API pricing page for current rates, which are updated with each model release.

Claude vs. ChatGPT: Key Differences

Both Claude and ChatGPT are AI assistants built on large language models, and both offer a free tier plus paid plans starting at $20/month. The differences come down to emphasis:

  • Coding and reasoning: Claude is frequently preferred for complex coding tasks, architectural decisions, and long-document analysis.
  • Writing quality: Claude tends toward a cleaner, more natural prose style; ChatGPT output can be more formulaic.
  • Image generation: ChatGPT can generate images natively; Claude cannot (as of mid-2026).
  • Safety design: Anthropic’s Constitutional AI approach produces more consistent and explainable refusals.

Neither is universally superior. The practical choice depends on your use case — many developers and researchers use both.

In the News

Anthropic recently launched Claude Sonnet 5, delivering Opus-level capability at mid-tier speed and pricing. Read more in our brief: Anthropic Launches Claude Sonnet 5.

FAQ

Is Claude free to use?
Yes. The free tier at claude.com provides access without a credit card, subject to rolling usage limits. Claude Pro ($20/month as of July 2026) removes most limits and adds access to more capable models.

What is the difference between Claude’s model tiers?
Haiku is fastest and cheapest; Sonnet balances speed and capability for most tasks; Opus handles the most demanding reasoning and coding; Fable is the frontier tier for cutting-edge applications.

Is Claude safe for sensitive work?
Anthropic built Claude around its Constitutional AI approach, aimed at making the model helpful, harmless, and honest. Like all AI systems, Claude can make mistakes and should not be the sole basis for high-stakes decisions.

How does Claude compare to ChatGPT?
Both are capable AI assistants with similar pricing. Claude is often preferred for coding and long-document work; ChatGPT has broader multimodal features including image generation and an advanced voice mode. The best choice depends on the task.