Project Crossbow: Lessons from Refactoring a Large-Scale Internal Tool

Crossbow is an internal tool at Cloudflare used by its Technical Support Engineers to debug network issues from particular locations or individual servers. The tool was transitioned from a Product Engineering team to the Support Operations team in September last year. The Support Operations team, closely aligned with Cloudflare’s Technical Support Engineers, developed diagnostic tooling and Natural Language Processing technology to drive efficiency. Crossbow allows engineers to perform various activities such as running commands like traceroutes, cURL requests, and DNS queries, debugging product features, and performance using bespoke tools. The team deprecated the CLI (command line interface) and focused on improving the UI in Cloudflare’s internal tool for its Technical Support Engineers. They also redesigned the system architecture for Crossbow to adopt a more simple pub/sub pipeline and implemented a JWT authentication scheme. Through these improvements, usage of Crossbow increased by 4.5x within a four-week period. The team also deprecated other tools and rolled them into Crossbow, consolidating tooling and reducing overhead of developing support tooling across the business.