# ngspice

5 Hacker News commenters recommended ngspice and 5 criticized it, November 2025 to November 2026. It was recommended in 3 of 13 months.

**Verdict:** Free circuit simulator that people use for real engineering work. Critics call its core code dated, say it assumes outdated systems, and find switching to xschem clumsy.

## Why people recommend it

- Used for real engineering work (2 comments): "they were written to get a real job worth real money done" ([source](https://news.ycombinator.com/item?id=48079686)) "It was even able to do complex ngspice simulations." ([source](https://news.ycombinator.com/item?id=49574053))
- Functional, performance-tuned code base (2 comments): "That sounds like a perfectly functional project, to me." ([source](https://news.ycombinator.com/item?id=48078844)) "That code is also hyper-optimized for performance" ([source](https://news.ycombinator.com/item?id=48079746))

## What people warn about

- Dated, Fortran-era core code (3 comments): "the interface in the original spice core is a mess of string handling and building a custom shell experience" ([source](https://news.ycombinator.com/item?id=48096024)) "Ngspice shows its heritage from the days of Fortran far more than a modern code base would or should." ([source](https://news.ycombinator.com/item?id=48080734)) "The spice core that ngspice is built off is terrible code." ([source](https://news.ycombinator.com/item?id=48079478))
- Assumes outdated systems and hardware (3 comments): "I download on Mac, run `ngspice`, "Error: Can't open display: :0". I look in the code - hardcoded X11-era assumptions." ([source](https://news.ycombinator.com/item?id=48079394)) "this project is way behind time and is going to pose a lot of issues to new users" ([source](https://news.ycombinator.com/item?id=48079504)) "very far from optimized for modern CPUs" ([source](https://news.ycombinator.com/item?id=48081337))

## Alternatives hackers recommend

- [Diode](https://hackerapproved.com/p/diode.md): 17 recommend
- [LTspice](https://hackerapproved.com/p/ltspice.md): 10 recommend
- [SPICE](https://hackerapproved.com/p/spice.md): 8 recommend

## Cite as

Hacker Approved, "ngspice", https://hackerapproved.com/p/ngspice/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).