Envelope encryption, key wrapping, format-preserving encryption and Shamir secret sharing, built on audited RustCrypto primitives. Key material and plaintext live in RAM-locked memory that zeroes on drop.

Use it to

• Encrypt PII/PHI at the field level with per-record data keys
• Tokenize card PANs, SSNs and IBANs while preserving their format for legacy systems
• Split a master key k-of-n across officers with Shamir sharing

A price-time-priority matching engine with FIX 4.4 and ITCH/MoLD codecs. The match hot path performs no heap allocation — verified by a test that asserts it.

Use it to

• Run an exchange, dark pool or internal crossing engine
• Encode and parse FIX 4.4 order flow
• Ingest and translate ITCH market-data feeds

Relationship-based access control in the Zanzibar style: a policy DSL, a tuple store, permission checks and reverse lookups — answer "can user X do Y to Z?" in microseconds.

Use it to

• Model fine-grained permissions across teams, folders and documents
• Check access on the request path with predictable tail latency
• List every resource a principal can reach (reverse lookup)

A tamper-evident audit log: hash-chained entries with Merkle inclusion proofs, optional PII redaction on the write path, and crash-recovery replay — proof that a record was never altered.

Use it to

• Keep compliance trails you can cryptographically prove weren't tampered with
• Produce an inclusion proof for a single entry on demand
• Redact PII as it's written for SOC 2 / regulatory logging

In-memory HNSW similarity search with recall measured against brute-force ground truth, and a tunable ef knob to trade recall for latency. mmap save/load for fast cold starts.

Use it to

• Power semantic search and RAG retrieval over embeddings
• Find nearest neighbours with a recall target you can quote
• Generate recommendation candidates at low latency

In-memory, single node · 100k × 128-dim. Quote recall and QPS together.

A columnar store with vectorized (AVX2) scan, filter and aggregation operators, native encoding with LZ4, zone-map pruning, and the ability to read Parquet — embedded analytics without a separate database.

Use it to

• Run analytical scans and group-bys over millions of rows in-process
• Embed OLAP into an app without standing up a warehouse
• Query existing Parquet (snappy) data directly

Validated against Parquet (snappy) on the same data.

In-process stream processing: tumbling, sliding and session windows, p50/p99 quantile sketches, and complex-event patterns including absence detection. Steady state performs no allocation.

Use it to

• Compute real-time aggregations and rolling metrics over event streams
• Track p50/p99 latency with bounded-memory sketches
• Detect patterns like "A not followed by B within 100 ms"

A zero-dependency PDF and DOCX parser with text extraction and term + regex redaction. Validated against real Ghostscript-produced PDFs — classic xref, object streams and encrypted.

Use it to

• Extract text from PDFs and DOCX in an ingestion pipeline
• Redact sensitive terms and patterns before storage
• Process documents without a native/OS dependency

Figures are per-doc overhead on small fixtures; a practical PDF/DOCX subset, not a full renderer.