Co-founder & General Partner at Andreessen Horowitz.
Tools Marc Andreessen has publicly discussed or demonstrated using. Curated by Magpie's editorial team from podcasts, posts, and public stacks.
About
Marc Andreessen is co-founder and general partner of Andreessen Horowitz. Co-host of the a16z Podcast and one of the most active investor voices on the AI stack. Names specific tools across guest spots and essays.
Marc Andreessen treats ChatGPT as his daily AI workhorse and publicly shared his exact custom system prompt on X in April 2026, framing the LLM as a 'world class expert in all domains' that should be 'provocative, aggressive, argumentative, and pointed.' The post drew 2.1M views and meaningful criticism but it remains his most explicit public demonstration of how he prompts. On the a16z Podcast episode 'How Marc Andreessen Actually Uses AI' (Nov 2025) he frames the workflow as turning ChatGPT into a personal board of directors.
You are a world class expert in all domains. Your intellectual firepower, scope of knowledge, incisive thought process, and level of erudition are on par with the smartest people in the world.
Marc Andreessen has publicly attributed comedic scripts and creative output to Claude in his X posts, treating it as a creative-collaboration tool alongside ChatGPT. In his agent-architecture thesis he frames Claude as one of the swappable model components in a Language-Model + Bash + Plain Text Files + Cron Job stack, deliberately positioning it as interchangeable with GPT-5 so the agent's 'memories' live in files rather than the model.
Once again I insist that Claude is spontaneously generating these scripts entirely on its own. Lawsuits can be directed to Anthropic Inc., 548 Market St, San Francisco, CA 94104.
Marc Andreessen publicly called DeepSeek's release 'AI's Sputnik moment' in January 2025, treating the open-weights Chinese frontier model as a structural shift in the AI competitive landscape. He frames open-weights models like DeepSeek as a hedge against closed-API lock-in and an existence proof that frontier capability isn't gated to a single vendor.
Marc Andreessen lists Gemini alongside ChatGPT and Claude as the three frontier models operators should standardize on for daily AI productivity. He hasn't said publicly that Gemini is his personal pick, but he treats it as one of the small set of frontier interfaces worth running side by side and choosing per task.
Andreessen Horowitz is a Cursor backer and Marc Andreessen has discussed Cursor's strategy publicly as an example of the application layer doing 'backward integration' from frontier API calls to a custom in-house model. He hasn't said publicly that he codes in Cursor himself, but he holds it up as the canonical case study for how AI-first IDEs become full-stack model companies.
These tools have been mentioned by the people featured in podcasts, interviews, posts, and other public media. Source links and citations are included wherever possible. Magpie AI has no direct relationship with the people on these pages. Spot a missing tool or a wrong attribution? Suggest a correction →