Tach – Visualize and untangle your Python codebase
Hey everyone! We're Evan and Caelean, the authors of Tach. Tach lets you visualize the architecture of your Python codebase, and gives you the tools to incrementally improve it. It uses module boundaries to give teams the benefits of microservices without the deployment complexity. If your code has been getting tangled up as your team and codebase grows, Tach helps you move back in the right direction, incrementally and quickly. You can use Tach to incrementally adopt a "modular monolith" architecture [1], for better local reasoning and smoother feature development. Since our last Show HN…
In plain words
Tach is an open-source Python development tool that visualizes and analyzes codebase architecture to help teams organize growing projects. It identifies dependency tangles and provides tools to incrementally adopt modular monolith patterns, giving teams microservices-like organizational benefits without deployment complexity. Built in Rust for speed, Tach is free and used by teams at companies including NVIDIA and PostHog.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
Hey everyone! We're Evan and Caelean, the authors of Tach. Tach lets you visualize the architecture of your Python codebase, and gives you the tools to incrementally improve it. It uses module boundaries to give teams the benefits of microservices without the deployment complexity. If your code has been getting tangled up as your team and codebase grows, Tach helps you move back in the right direction, incrementally and quickly. You can use Tach to incrementally adopt a "modular monolith" architecture [1], for better local reasoning and smoother feature development. Since our last Show HN (https://news.ycombinator.com/item?id=41359181) we've shipped support for layers, third party dependencies, visualizations, and more. Tach is: * Open source (MIT) * completely free * fast (written in Rust) * in use by teams at NVIDIA, PostHog, and more. One way Tach differs from existing systems that handle this problem (build systems, import linters, etc) is the ability to be incrementally adopted. Also, runtime speed. If you struggle with dependencies, onboarding new engineers, or a massive codebase, Tach is for you! We built it with developers in mind - with clean integrations into Git, CI/CD, and IDEs, and the performance for it to be effective in any form factor. [1] https://www.milanjovanovic.tech/blog/what-is-a-modular-monol...
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