After the Rust cutover: offline-first invoicing, a real tax engine, and one loud week of shipping
The build-in-public series covered the rewrite — fifteen chapters of porting a .NET invoicing SaaS to Rust. The cutover happened on a Tuesday. This post is about everything that came after : the first week running Rust in production, the bugs real users found, and the features that turned a fast backend into a product freelancers can bet their invoicing on. Try it on a real workspace: FoxyInvoice…
Seven days after the Rust cutover, the newly-produced invoicing SaaS, FoxyInvoice, delivered a range of significant features. First, it introduced offline-first invoicing, enabling drafts to be saved as you type and survive browser crashes. Changes are queued and replayed when the connection is restored, allowing users to continue working without interruption.
Additionally, FoxyInvoice developed a tax engine that allows businesses to declare their tax nexus per state. This engine only applies taxes where the business has declared a collection obligation, meaning invoices with no nexus are correctly taxed as zero. The engine also provides detailed exports of year-end invoices, available in CSV, QuickBooks IIF, or Tally XML formats, ensuring accurate financial records.
FoxyInvoice's payment methods section now supports PayPal, Venmo, Stripe links, and full bank details, which are printed on invoices and displayed on payment pages. A redesigned PDF now features branded headers, multi-page flow with page numbers, per-line tax amounts, and visible discounts, all of which match the server's calculations.
Lastly, FoxyInvoice added multi-company functionality, allowing users to manage up to five companies from a single login. Each company has isolated data, numbering, and branding. Users can also share quotes with clients, who can accept or decline them directly through the quote page, resulting in a faster invoicing process.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
