Claude (Anthropic)

Claude is the family of large language models developed by Anthropic, an AI safety company founded in 2021 by former OpenAI researchers. The current flagship in 2026 is Claude Opus 4.7, which leads developer benchmarks for code generation, long-document reasoning, and tool use, and is the model behind Claude Code (Anthropic's coding agent), claude.ai, and the Anthropic API.

Anthropic differentiates Claude on three fronts: a "constitutional AI" training method that bakes safety principles into the model rather than bolting them on, a 1M-token context window that enables whole-codebase analysis in a single request, and a steerable, transparent personality that developers find easier to work with on long tasks.

The Claude model family

In 2026, Anthropic ships three Claude tiers, each with checkpoint updates labeled by minor version (e.g., 4.5, 4.6, 4.7):

• Claude Opus 4.7 — Frontier reasoning; favored for code, agentic workflows, and complex analysis.
• Claude Sonnet 4.7 — Balanced cost/quality; the workhorse for production deployments.
• Claude Haiku 4.7 — Fastest and cheapest; great for high-volume classification, extraction, and simple generation.

Each tier supports the same 1M-token context window (vs. GPT-5 at 256k–1M and Gemini at 1M+), vision input, tool use, and structured output. Pricing in 2026: Opus ~$15/$75 per M input/output tokens, Sonnet ~$3/$15, Haiku ~$0.80/$4.

What Claude is known for

Anthropic's models consistently lead on:

• Code generation — Claude Opus 4.7 tops SWE-Bench and HumanEval; powers Claude Code, Cursor, and GitHub Copilot's "premium" tier.
• Long-document analysis — 1M-token context handles entire books, codebases, and document corpora without chunking. Recall remains high deep into context (no "lost in the middle" failure that plagued earlier 100k+ models).
• Tool use and agency — Anthropic invested heavily in tool-use training; Claude reliably invokes tools, parses responses, and chains actions. This makes it the default model for AI agents.
• Constitutional AI — Trained with a "constitution" of principles (helpful, harmless, honest), reducing the over-refusal that frustrates GPT users while maintaining safety.

A 2026 Stack Overflow developer survey found Claude was the most-used AI coding assistant among professional developers (43%), edging out GitHub Copilot (41%) and ChatGPT (35%).

Examples of Claude in production

1. Claude Code — Anthropic's official terminal coding agent; widely adopted by engineering teams.
2. Cursor — AI-first IDE; Claude is the default model for "Composer" mode.
3. Notion AI — Uses Claude for long-document Q&A and writing assistance.
4. DuckDuckGo AI Chat — Claude is a model option alongside GPT and Llama.
5. Slack AI — Channel summaries, thread recaps, and search are Claude-powered.

How PostKit relates to Claude

PostKit doesn't currently use Claude in its production pipeline (Gemini Flash 3 wins on cost/latency for short structured generation), but Claude is heavily used by founder Tadeáš Raška for development. The PostKit codebase, prompts, and architecture documentation were built with Claude Code as a coding partner.

For brands building on top of PostKit who want to extend functionality (custom integrations, white-label deployments, vertical-specific prompt packs), Claude is the recommended model for orchestration logic. Its reliability on tool use and long-context reasoning makes it the right choice for the "controller" layer above PostKit's content generation.

Frequently asked questions

Why "Claude"? Named after Claude Shannon, the father of information theory.

Is Claude better than ChatGPT? For code, long documents, and agentic tool use: typically yes in 2026. For creative writing, image generation, and voice: GPT-5 retains an edge. Best practice is to evaluate both on your specific task.

What is "constitutional AI"? A training method where the model learns to evaluate and revise its own outputs against a written set of principles ("be helpful, avoid harm, be honest"). Reduces reliance on per-query human feedback for safety alignment.

How long is Claude's context window? 1 million tokens for Opus 4.7 and Sonnet 4.7 (~750,000 words). The largest production context in 2026, tied with Gemini 2.5 Pro.

Does Claude have memory across conversations? Claude.ai supports project-level memory and a "Projects" feature for persistent context. The API is stateless — pass prior turns in each request.

Can Claude generate images? Not natively. Claude is text + vision input, text output. For image generation, pair it with Imagen 3, DALL-E 3, or Flux.

Is Claude open-source? No. Claude weights are proprietary. Anthropic publishes research papers and partial system documentation but does not release model weights.

What's "Claude Code"? Anthropic's official coding CLI/agent that uses Claude Opus to read your codebase, plan changes, edit files, run commands, and submit PRs. It's the leading agentic coding tool in 2026.

Related terms

• LLM (Large Language Model)
• GPT-4 / GPT-5
• Gemini (Google)
• Generative AI
• AI agent
• Multimodal AI
• Prompt engineering
• RAG (Retrieval-Augmented Generation)

Sources

• Anthropic — Claude Model Card (2025–2026)
• Anthropic — Constitutional AI Paper (2022)
• Stack Overflow Developer Survey 2026