Centinel vs Castle
Castle stops account abuse with a fingerprint SDK that runs edge + in-app. Centinel detects and manages AI crawlers with a 1,600-profile database and per-crawler policy controls. The question is which problem you are solving.
Castle is a 26-page developer-first site. An SDK drops into your app; an edge integration wires into Cloudflare or your own proxy. Pricing is published: free up to 1,000 API calls per month, $0.002 per call after that. Customers are B2C apps — GitBook, Housecall Pro, Rue La La, Touch of Modern. Castle is rooted in device fingerprinting and rule-engine fraud: fake accounts, ATO, SMS pumping, card testing. Centinel is rooted in AI crawler detection and management: 1,600+ named crawlers, per-crawler policy controls, crawler analytics. Both publish pricing. Both offer a free tier. Both run at the edge. The question is which problem you are solving — account abuse or bot traffic management.
Why teams pick Centinel over Castle
Castle's fraud primitives are aimed at B2C app abuse — fake accounts, ATO, card testing. Centinel is aimed at AI crawlers, content protection, and per-crawler policy controls. Different problem, different database, different buyer.
Try Centinel freeFrequently asked questions
- Is Castle a competitor to Centinel?
- Adjacent, not overlapping. Castle is a developer-first device fingerprint SDK aimed at B2C account fraud — fake signups, account takeover, card testing, SMS pumping. Centinel is an AI crawler identity and bot management layer for publishers. Both publish pricing, both run at the edge, both have free tiers. The question is which fraud you are stopping.
- Can Castle detect AI crawlers?
- Partially. Castle's fingerprint surface will flag headless browsers and generic automation, but its classifiers are trained on account-abuse patterns, not on identifying specific AI training crawlers. Centinel's 1,600-plus crawler profiles map directly to known AI companies, crawl purposes, and compliance postures — a depth Castle does not claim because it is solving a different problem.
- What does Castle charge?
- Castle publishes pricing: free up to 1,000 API calls per month, $0.002 per call after that. Centinel also publishes pricing, with a free audit tier and per-request validation pricing scoped to your traffic. The commercial models are comparable in transparency; the product scope is what differs.
- Should I run Castle and Centinel together?
- If your site has both an account-fraud surface (logins, signups, payments) and an AI-crawler exposure (content, docs, pricing), yes — they cover disjoint attack surfaces. Many SaaS teams do exactly this: Castle on the auth layer, Centinel on the content layer, routed through the same Cloudflare Worker. Neither replaces the other.
Pick the next step that fits where you are
Demo, self-serve check, pricing, or a quiet email. Whichever maps to your stage.