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Show HN: Helios – what plug-in solar could generate for any address in Britain

https://helios.southlondonscientific.com/
60•ruaraidh•4h ago•14 comments

Show HN: Tiny-vLLM – high performance LLM inference engine in C++ and CUDA

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171•yu3zhou4•20h ago•15 comments

Show HN: Open-source private home security camera system (end-to-end encryption)

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Show HN: Jynx, a matchmaking app to find gaming teammates

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160•dtagames•23h ago•46 comments

Show HN: Zot – Yet another coding agent harness

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88•patriceckhart•1d ago•76 comments

Show HN: I built an Android OS in the browser

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Show HN: VT Code – open-source terminal coding agent in Rust

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Show HN: Ktx – Open-source executable context layer for data agents

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Show HN: Continue? Y/N: A 60-second game about AI agent permission fatigue

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376•Wirbelwind•2d ago•156 comments

Show HN: Free activity calendar for schools, sports clubs, and organizations

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6•glenn_vc•17h ago•6 comments

Show HN: Context-aware Japanese furigana using Sudachi and ModernBERT

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Show HN: Promptloop – create, run, and improve prompt evals from the terminal

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11•velapod•23h ago•2 comments

Show HN: Hallucinate – Massively Multiplayer Online Rave

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435•stagas•2d ago•193 comments

Show HN: Open-Source AI Racing Harness

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74•danAtElodin•2d ago•22 comments

Show HN: Self Publish Studio

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Show HN: AionOS – self-healing microkernel in Zig (boots on real hardware)

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Show HN: A Claude Code skill that scopes problems like Peter Naur

https://github.com/spinchange/cartographer-skill/blob/main/skills/cartographer/SKILL.md
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Show HN: Oort – A prompt library where every listing has a shipped project

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Show HN: I brought back Airbnb categories

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5•giulioco•19h ago•0 comments

Show HN: Open-source Workspace (mail,docs,spreadsheet,drive) web/iOS

https://tinycld.org/
109•nathanstitt•3d ago•39 comments

Show HN: I made an emergency page for my family

https://help.delduca.org
82•delduca•3d ago•104 comments

Show HN: Local-first semantic knowledge graph with magnetic-pull retrieval

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82•craigmccaskill•3d ago•60 comments

Show HN: MigraDiff – maintained fork of migra (PostgreSQL schema diff)

https://github.com/migradiff/migra
4•lateos-ai•19h ago•2 comments

Show HN: I built a better GitHub search that rank repos by what matters

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5•donghaxkim•20h ago•2 comments

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Show HN: A website that tracks every stock trade Congress makes

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61•hubraumhugo•3d ago•24 comments

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Show HN: NvEnvy – A Notational Velocity (NvAlt) Reboot in Swift. OSS

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3•hank2000•23h ago•0 comments
Open in hackernews

Show HN: Fahmatrix – A Lightweight, Pandas-Like DataFrame Library for Java

https://github.com/moustafa-nasr/fahmatrix
46•mousomashakel•1y ago
Hey HN, I’ve built Fahmatrix, a minimal, fast Java library for working with tabular data — inspired by Python’s pandas, but designed for performance and simplicity on the JVM.

After working extensively with Python’s data stack, I often ran into limitations related to speed, especially in larger or long-running data workflows. So I built Fahmatrix from scratch to offer similar APIs for manipulating CSVs, performing summary statistics, slicing rows/columns, and more — but all in Java.

Features:

Lightweight and dependency-free

CSV/TSV import with auto-headers

Series/DataFrame structures (like pandas)

describe(), mean(), stdDev(), percentile() and more

Fast parallel operations on numeric columns

Java 17+ support

Docs: https://moustafa-nasr.github.io/Fahmatrix/ GitHub: https://github.com/moustafa-nasr/fahmatrix

I’d love feedback from the Java and data communities — especially if you’ve ever wanted a simple dataframe utility in Java without needing full-scale ML libraries.

Happy to answer any questions!

Comments

rickette•1y ago
Congrats on putting this out there. There isn't a de facto pandas-like library in Java like you said. But for Kotlin there is: https://github.com/Kotlin/dataframe
mousomashakel•1y ago
Thanks so much! Yep, I’ve seen the Kotlin DataFrame lib — very elegant. Fahmatrix is meant for plain Java users who want similar capabilities without switching ecosystems. Appreciate the support!
uwemaurer•1y ago
Always great to see efforts to make working with data frames easier. Here are some similar data frame libraries for Java:

https://github.com/jtablesaw/tablesaw

https://github.com/dflib/dflib

My preferred way is just use duckdb java API. I didn't see anything better in performance/efficiency. Also a SQL query is often easier to write

theanonymousone•1y ago
Yes. It has bothered me for a long time too. Maybe the best mix is a dataframe library with basic operations (column select, non-null etc), which also allows SQL for more complex stuff?
radus•1y ago
Polars and duckdb interoperate nicely and can enable this flexibility
theanonymousone•1y ago
Does Polars have a Java library?
mousomashakel•1y ago
Totally agree that SQL can be the best tool for many jobs. My goal with Fahmatrix is to serve the opposite niche: where devs want something that's Java-native, procedural, and simple without reaching for an external engine. SQL support or DSL might come later though — I see the appeal.
skanga•1y ago
What about Tablesaw, Apache Arrow? How does this compare ...
mousomashakel•1y ago
Good question. I’ll publish benchmarks soon, but the core difference is that Fahmatrix is fully Java, no JNI, and minimalistic — ideal for small projects or environments like Android. Tablesaw and Arrow are more powerful, but heavier. Fahmatrix aims to be the “just enough” middle ground.
owlstuffing•1y ago
Nice!

I’m currently using manifold-sql with duckdb for this.

mousomashakel•1y ago
Thanks! That’s a great combo — manifold-sql + duckdb gives you strong typing with powerful SQL under the hood. Fahmatrix is aiming to complement that approach for cases where you want quick, native Java code without SQL — e.g., when building data flows or custom logic inline. Would love to hear if you’ve hit any pain points that a Java-native approach could help with.
theanonymousone
•
1y ago
Sure. So maybe notehr comment would be to make it (particularly the Series class), as compatible with Java Streams as possible.

Next step would likely be compatibility with popular libraries such as Apache Commons Math: https://commons.apache.org/proper/commons-math/userguide/sta...

mousomashakel•1y ago
Thanks! I'm aware of those great projects. Fahmatrix aims to offer a lightweight, dependency-free alternative that’s easy to embed in any Java app. DuckDB is super impressive, especially for SQL-heavy tasks — but my goal is more about a native, fluent API for those who prefer direct Java code over SQL.