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Product Recommendations Engine

An open-source real-time product recommendation engine built as a Harper component. Combines co-occurrence learning, HNSW vector search, UCB exploration, and category diversity re-ranking on Harper's replicated tables. No vector database, training pipeline, or external ML infrastructure required.
TypeScript
Repo
TypeScript

Product Recommendations Engine

at Harper
April 26, 2026
at Harper
April 26, 2026
at Harper
April 26, 2026
April 26, 2026
An open-source real-time product recommendation engine built as a Harper component. Combines co-occurrence learning, HNSW vector search, UCB exploration, and category diversity re-ranking on Harper's replicated tables. No vector database, training pipeline, or external ML infrastructure required.
An open-source real-time product recommendation engine built as a Harper component. Combines co-occurrence learning, HNSW vector search, UCB exploration, and category diversity re-ranking on Harper's replicated tables. No vector database, training pipeline, or external ML infrastructure required.

Download

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An open-source real-time product recommendation engine built as a Harper component. Combines co-occurrence learning, HNSW vector search, UCB exploration, and category diversity re-ranking on Harper's replicated tables. No vector database, training pipeline, or external ML infrastructure required.

Download

White arrow pointing right
An open-source real-time product recommendation engine built as a Harper component. Combines co-occurrence learning, HNSW vector search, UCB exploration, and category diversity re-ranking on Harper's replicated tables. No vector database, training pipeline, or external ML infrastructure required.

Download

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Explore Recent Resources

Comparison
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Kafka-Centered Stacks vs. a Single Harper Cluster: Where Real-Time Latency Actually Comes From

End-to-end latency in real-time pipelines comes from coordination across systems, not from any single component. Four common workloads, tested two ways, show where multi-hop architectures compound delays and where collapsing storage, messaging, and compute into one runtime changes the math.
Cache
Comparison
End-to-end latency in real-time pipelines comes from coordination across systems, not from any single component. Four common workloads, tested two ways, show where multi-hop architectures compound delays and where collapsing storage, messaging, and compute into one runtime changes the math.
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Aleks Haugom
Senior Manager of GTM
Comparison

Kafka-Centered Stacks vs. a Single Harper Cluster: Where Real-Time Latency Actually Comes From

End-to-end latency in real-time pipelines comes from coordination across systems, not from any single component. Four common workloads, tested two ways, show where multi-hop architectures compound delays and where collapsing storage, messaging, and compute into one runtime changes the math.
Aleks Haugom
Jun 2026
Comparison

Kafka-Centered Stacks vs. a Single Harper Cluster: Where Real-Time Latency Actually Comes From

End-to-end latency in real-time pipelines comes from coordination across systems, not from any single component. Four common workloads, tested two ways, show where multi-hop architectures compound delays and where collapsing storage, messaging, and compute into one runtime changes the math.
Aleks Haugom
Comparison

Kafka-Centered Stacks vs. a Single Harper Cluster: Where Real-Time Latency Actually Comes From

End-to-end latency in real-time pipelines comes from coordination across systems, not from any single component. Four common workloads, tested two ways, show where multi-hop architectures compound delays and where collapsing storage, messaging, and compute into one runtime changes the math.
Aleks Haugom
Tutorial
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Your API cache is secretly a database

Most teams treat a cache as a black box: URL-keyed blobs with a TTL, useful for speed and nothing else. In Harper, cached data lands in a real table inside the same query engine. That means filtering, joining, real-time subscriptions, and vector search all work against it.
Cache
Tutorial
Most teams treat a cache as a black box: URL-keyed blobs with a TTL, useful for speed and nothing else. In Harper, cached data lands in a real table inside the same query engine. That means filtering, joining, real-time subscriptions, and vector search all work against it.
Person with very short blonde hair wearing a light gray button‑up shirt, standing with arms crossed and smiling outdoors with foliage behind.
Kris Zyp
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Tutorial

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Most teams treat a cache as a black box: URL-keyed blobs with a TTL, useful for speed and nothing else. In Harper, cached data lands in a real table inside the same query engine. That means filtering, joining, real-time subscriptions, and vector search all work against it.
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Tutorial

Your API cache is secretly a database

Most teams treat a cache as a black box: URL-keyed blobs with a TTL, useful for speed and nothing else. In Harper, cached data lands in a real table inside the same query engine. That means filtering, joining, real-time subscriptions, and vector search all work against it.
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Your API cache is secretly a database

Most teams treat a cache as a black box: URL-keyed blobs with a TTL, useful for speed and nothing else. In Harper, cached data lands in a real table inside the same query engine. That means filtering, joining, real-time subscriptions, and vector search all work against it.
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Tutorial
GitHub Logo

Introducing Structon: Random-Access Binary Encoding for JavaScript

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Tutorial
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Person with very short blonde hair wearing a light gray button‑up shirt, standing with arms crossed and smiling outdoors with foliage behind.
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SVP of Engineering
Tutorial

Introducing Structon: Random-Access Binary Encoding for JavaScript

Deserializing entire records to read one field is a bottleneck at scale. Structon stores objects in a binary format where any field is reachable by byte offset, with lazy getters that never allocate until you access a property. It's the encoding Harper has used internally for years, now a standalone package.
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Tutorial

Introducing Structon: Random-Access Binary Encoding for JavaScript

Deserializing entire records to read one field is a bottleneck at scale. Structon stores objects in a binary format where any field is reachable by byte offset, with lazy getters that never allocate until you access a property. It's the encoding Harper has used internally for years, now a standalone package.
Kris Zyp
Tutorial

Introducing Structon: Random-Access Binary Encoding for JavaScript

Deserializing entire records to read one field is a bottleneck at scale. Structon stores objects in a binary format where any field is reachable by byte offset, with lazy getters that never allocate until you access a property. It's the encoding Harper has used internally for years, now a standalone package.
Kris Zyp