QuillBot

Claude is Anthropic's family of AI assistants, known for long-context reasoning, careful writing and strong coding ability. The Opus, Sonnet and Haiku tiers let you trade off intelligence, speed and cost. Claude excels at nuanced analysis, document understanding and agentic coding workflows, and is a favourite among developers and writers who value clarity.

ChatGPT is OpenAI's flagship conversational AI, powering hundreds of millions of weekly users across web, mobile and API. Built on the GPT-4o and GPT-5 family of models, it handles text, images, voice and code in a single interface. With browsing, data analysis, custom GPTs and a vast plugin ecosystem, it remains the default assistant for most knowledge workers.

Gemini is Google's natively multimodal model family, deeply integrated across Search, Workspace, Android and the Pixel line. Its standout feature is an enormous context window of up to one to two million tokens, ideal for analysing long videos, codebases and document sets. Gemini blends Google's real-time knowledge with strong reasoning and is available free in many products.

Perplexity is an AI answer engine that combines live web search with large language models to deliver cited, up-to-date answers. Instead of a blank chat, it returns sourced summaries with follow-up questions, making it a popular replacement for traditional search. Pro mode taps frontier models and deeper research, and its API exposes the same search-grounded answers.

Grok is xAI's assistant, tightly integrated with the X platform and trained with a distinctively candid, witty persona. It has real-time access to X posts, giving it an edge on breaking news and live sentiment. Grok offers strong reasoning, image generation and a less filtered conversational style than most competitors.