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.
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? A Complete Guide With 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 for AI search visibility
ChatGPT UI vs API tracking for AI search visibility. Promptwatch put the same commercial prompts through both routes... They came back describing two different markets.
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.
The Complete Guide to LLM Crawler User Agents: Who's Reading Your Website in 2025?
AI crawlers now visit 1 in 4 websites daily. Learn which bots are reading your content, why it matters, and how to optimize for maximum AI visibility.
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.
