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Castle is a Y Combinator company in the Winter 2016 batch. Its directory entry describes it as: Block bots & bad behavior. The founders listed are Johan Brissmyr (Founder/CEO), Sebastian Wallin (Founder/CTO) (Y Combinator directory entry, November 15, 2015).
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Example from a real report (our sample on Target): “Target eliminated approximately 1,800 corporate positions, with around 1,000 employees receiving layoff notices and the remainder accounted for by eliminating open roles.” Source: NBC News
A complete suite of SDKs and APIs to monitor users, block bots, and stop in-app fraud.
The title and description the site itself served, answering 200. Not a cached copy and not the company's directory entry — what was live when we asked.
Counted only where a thread links to this company's own site, announces it by name on that forum, or names it beside its own Y Combinator batch. A thread whose title merely carries the words is not counted — a name is not an identifier. More may exist than the one page of results read here. Hacker News is not us, and nothing above is our opinion of the company.
Johan Brissmyr
Founder/CEO
Sebastian Wallin
Founder/CTO
Founders, titles and bios as the company published them. Photographs are our own copies of the ones on that record, so they do not break when the original link expires.
No investor is drawn from a Form D — the form states how many invested and never who. The one investor on this graph is named because a batch has exactly one.
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Example from a real report (our sample on Target): “Target eliminated approximately 1,800 corporate positions, with around 1,000 employees receiving layoff notices and the remainder accounted for by eliminating open roles.” Source: NBC News
A Full Report on Castle: verified, sourced, every claim cited, ready in a few minutes. See pricing.
What the Full Report on Castle covers
The Short Answer
Which Company This Is
What They Do, And How The Money Works
Who Runs It, And How To Reach Them
The Money: Funding, Valuation, Runway
Who Pays Them, And Who They Are Up Against
Warning Bells
Sources
11 cited sources found
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If you're behind Castle: acceptance into a YC batch is one of the few weeks a young company gets looked up by people who matter — investors, other founders, press. FoxPlug turns the commits, deploys, and releases you're already making into that story automatically, so anyone who looks finds something current. GetFoxChat puts a guide on your own site so the people YC's own page just sent you don't read one line and leave.
Sourced from the company's Y Combinator directory entry, from the company's own site, read directly on 2026-09-27 (castle.io), from the public GitHub account that record links to (castle), and from Hacker News, where 29 threads met the matching rule stated beside the count.
