Klaas is Co-Founder & CTO of Promptwatch, the AI visibility platform he launched in 2025 with Gijs de Groot to help brands understand and improve how they're represented across ChatGPT, Claude, Gemini, and Perplexity. Under his technical leadership, Promptwatch now processes over 100 million data points a day and serves more than 1,800 organizations, including Duolingo, Fireflies, and Monks. He studied at Utrecht University before moving into software engineering, and writes for the Promptwatch blog on how AI search engines actually retrieve, rank, and cite content.
Which LLM Models to Track for Brand Visibility in 2026
ChatGPT, Gemini, AI Overviews, Perplexity or Claude? Promptwatch's framework for choosing which LLM models to track, based on your buyers, your market and how each engine cites sources.
How AI Coding Agents Choose Which SDK, Library, or API to Install
Claude Code and Codex pick tools from training data, live search, project context, and what runs. Here's how each input works and how Promptwatch measures the result.
Coding Agent Visibility: How to Track Whether Claude Code and Codex Recommend Your Product
Claude Code and Codex install the tools they recommend. Here's how SaaS teams can use Promptwatch to track whether coding agents pick their product or a competitor's.
How to Choose an AI Visibility Tool with Google Search Console Integration
An AI visibility tool with Google Search Console integration should join clicks and rankings to AI citations page by page. Here's what to look for, and how Promptwatch does it.
What Are AI Crawler Bots? Types, Examples and 30 Days of Real Crawl Data
AI crawler bots explained: what GPTBot, ClaudeBot, and PerplexityBot actually do, illustrated with 30 days of real crawl logs Promptwatch pulled from a live customer site.
Why Did ChatGPT Stop Citing Reddit? Inside the August 2026 Citation Collapse
Reddit's share of ChatGPT Search citations fell 86% in a week. Promptwatch's own citation data shows why, and what to track instead.
ChatGPT UI vs API Tracking: What our tests Reveal About AI Visibility Data
Promptwatch ran the same prompts through the ChatGPT interface and the API. They shared 25.6% of sources. Here's what API tracking misses, even with web search on.
New Feature: Ads Radar: see who is advertising inside AI answers
AI search now shows sponsored placements. Promptwatch's Ads Radar finds them automatically and shows which advertisers appear on your prompts, their ad copy, and where they send the traffic.
What Is Generative Engine Optimization (GEO)? Definition, Origin & Examples
What generative engine optimization (GEO) is, where the term came from, what the KDD 2024 research found, how companies use it, and how to get started.
LLM Crawler User Agents: The Complete 2026 List of AI Bots, Tokens and IP Ranges
Every LLM crawler user agent from OpenAI, Anthropic, Google, Perplexity, Meta and more, with robots.txt tokens, IP lists and copy-ready templates, checked by Promptwatch.
LLMs.txt Is Largely Ignored: Why It Has No Impact on AI Search or GEO (For Now)
Despite the hype, llms.txt is being crawled by some bots but not used by major AI search engines. Here’s the evidence, Google’s statements, and what to prioritize instead.
How ChatGPT Searches the Web in 2026: What Promptwatch's Fan-Out Data Shows
How ChatGPT turns a prompt into search queries, what changed in 2026 (fewer, shorter searches, site: queries, fewer citations), and how to optimize for it, from Promptwatch data.
Why You're Invisible in AI Search (and What to Do About It)
Your focus on Google rankings might be blinding you. Your competitors are already showing up in ChatGPT, Perplexity, and Claude – are you?
Why Generative Engine Optimization (GEO) Matters More Than Ever
As AI tools become go-to sources for information, optimizing your brand presence for generative engines is now essential.
Be the brand AI recommends
Monitor your brand's visibility across ChatGPT, Claude, Perplexity, and Gemini. Get actionable insights and create content that gets cited by AI search engines.
