16:T574,Hey HN,

I'm a solo founder running a service business through an Estonian e-Residency company (OÜ). Every time I invoiced a client in another EU country, I had to manually check if reverse charge applies, validate their VAT number on VIES, and figure out the correct tax treatment. I got tired of Googling the same rules over and over, so I built the tool I wanted.

Invoxo automatically determines the correct VAT treatment for each invoice based on seller/buyer countries, VAT registration status, and buyer type. It covers:

- VIES VAT number validation (real-time, with proof retention) - Reverse charge auto-detection for EU B2B - OSS handling for B2C digital services - Immutable tax records locked at issuance

The tax engine routes every invoice through a regime-specific decision system — no hardcoded rules in the UI layer. Tax payloads are versioned and hashed for audit.

It's built for service businesses only — no goods, no customs, no margin schemes. That constraint keeps the tax logic correct rather than approximately correct.

Stack: Laravel, TaxRegimeRouter that isolates each regime's decision logic, treatments, and payload schemas.

14-day free trial, plans from €19/month.

https://invoxo.eu

Happy to answer questions about EU VAT edge cases or the architecture.17:T4b6,Hi HN — I just open-sourced Hibana and hibana-agent.

Hibana is an Affine MultiParty Session Types (MPST) runtime for Rust.

It targets protocol drift in distributed systems. Instead of maintaining separate hand-written state machines in each component, you define interaction once as a global choreography and project role-local behavior at compile time. At runtime, only valid protocol transitions are executable, so invalid moves such as skipping, reusing, or taking the wrong branch are rejected by the protocol model.

The practical value is that one global source of truth replaces multiple hand-written state machines and re

Deep dive into the challenges of building Kafka on top of S3