Fake Googlebot visits are #1 in website logs I've been working on. At the beginning I was fighting with them using Cloudflare ASN block rules or their managed Bot Fight mode but it appeared to be not only pointless, but also harmful for my websites.
Bot Fight mode randomly started blocking real Bing / Google / OpenAI crawlers what wasted crawling budget and discouraged crawlers to revisit updated pages.
Sometimes it's better to not fight with bots actively but harden environment and only react for the worst offenders.
For Google it's pretty straight forward to throw away fake crawlers by just only allowing their published list of crawler IPs so you don't accidentally allow someone from a random GCP IP to crawl you if unwanted (https://developers.google.com/crawling/docs/crawlers-fetcher...).
Fully supporting privacy-first approach in utilities like yours. TBH I built an internal tool like this for the company I was working on my previous contract.
It would be great if you add a possibility to change the drawing or font color. Even few presets would be enough.
P.S. Just noticed. You have GA tracking implemented. It doesn't guarantee privacy so I would recommend changing it to PostHog and excluding area from every tracking and sessions recording.
I really like that you implemented multiple modes and additional views for some file types. Only noticed that in XLSX "tab", switching to the PDF occasionally fails to generate PDF preview - worker reliability issue. You may think of adding some caching based on files checksum, even free Cloudflare plan R2 storage would be enough.
I built a browser tool for querying local Parquet, CSV, JSON, Excel, Arrow, Avro, DBF, and SQLite files with DuckDB-WASM.
Most probably after DuckDB v2.0 release I will revamp my tool as well.