What is vcal-core?

vcal-core is a lightweight Rust library for building fast semantic caches and vector indexes using HNSW. It lets you store embeddings, perform nearest-neighbor search, and implement cache-like reuse in LLM applications.

Highlights

• HNSW index (Cosine / Dot)
• Insert / Upsert / Delete (soft tombstone)
• TTL and capacity-based eviction (optional)
• Batch search
• Snapshot support via serde (byte-based serialization)
• Fully safe Rust (#![deny(unsafe_code)])

When to use vcal-core

• You want an in-process vector index with zero network hops
• You need predictable performance and control over lifecycle (TTL/eviction)
• You are building a semantic cache or retrieval layer inside your application
• You don’t need a distributed vector DB for this component

See Quickstart → minimal example in Rust.