Perseus

Perseus is a retrieval engine purpose-built for coding agents, grounding them in real code with citations to exact file and line. Instead of relying on generic file exploration or stale context, Perseus indexes your working tree—including uncommitted edits—and returns ranked, cited results in about a second. It is designed for developers and AI agent tool builders who need fast, accurate code search by meaning and structure. Key features include semantic code search, multi-hop search that follows threads across files, research packets combining multiple questions, impact analysis before editing shared symbols, and incremental re-indexing of the working tree. Perseus integrates via CLI with --json output and an HTTP API, and supports structural parsing for Go, Rust, and Ruby since March 2026. The Perseus console lets you run queries, watch the planner search your codebase live, and open citations. Perseus is Y Combinator backed and offers a one-time Demo week ($5/7 days), Developer ($20/seat/month), and Scale ($100/seat/month) plans. It runs as a CLI tool and HTTP API, with plans to expand language coverage and integration depth. What sets Perseus apart is its focus on latency and citation accuracy: queries complete in about a second with exact line ranges, making it a strong alternative to generic code search tools or grep.