Automating the part of running a trade business nobody enjoys

Every Danish tradesperson running their own invoicing knows the feeling: an invoice is two weeks overdue, and now someone has to decide whether to send a reminder, write it, and actually send it, on top of the day's real work. It's a small task that's easy to forget and slightly uncomfortable to do, which is exactly the combination that makes it get skipped. Welkent's rykkerflows exist to make sure it doesn't.

A ladder, not a single reminder

A rykkerflow is a fixed escalation ladder: reminder steps at 7, 14, and 30 days after an invoice becomes overdue, each with its own customizable text. A gentle nudge at day 7 reads very differently from a firmer notice at day 30, and Welkent lets a business write each step's wording once, rather than composing a reminder by hand every time. Once a flow is turned on for an account, it runs against every overdue invoice on that schedule without anyone having to remember to trigger it.

The reminders are the easy part. The safety rules are the product.

Building a scheduler that fires off emails on a timer is not, by itself, hard. What's actually hard (and what determines whether a business trusts an automated dunning system enough to turn it on) is everything that has to stop it from doing something embarrassing or wrong. Welkent's rykkerflows enforce four rules that exist specifically because of what happens if you don't have them:

1. Paid stops it, immediately. If an invoice is marked paid, any scheduled reminder for it is cancelled before it goes out. There is no worse advertisement for an automated system than a customer receiving a stern payment reminder for something they already paid. It doesn't just look sloppy, it actively damages the relationship the invoice was for.
2. No burst sending. Reminders go out at a controlled pace rather than all at once, so a business with a large batch of overdue invoices doesn't accidentally trigger what looks like a mass email blast from a payment-collection address.
3. Never send the same step twice. Each rung of the ladder fires exactly once per invoice. A retry, a redeploy, or a scheduler hiccup should never result in a customer getting the 14-day reminder two days apart.
4. A bounce escalates to a person, not silence. If a reminder email bounces, that's a signal something is actually wrong (the wrong address, a full inbox, a customer who's stopped checking that account), and the flow hands that invoice off as a task for a human to call, rather than quietly failing and leaving the invoice to age with no reminder ever successfully delivered.

That last rule is the one that reveals what the feature is really for. An automated reminder that silently fails to deliver is worse than no automation at all, because it creates false confidence that the business is on top of collections when it isn't.

A quieter constraint: the PDF has to exist before the worker runs

One detail that shaped the implementation: the background worker that sends these reminders runs on a schedule, with no logged-in user and no active session token. But rendering an invoice PDF, in Welkent, normally happens as part of a request a signed-in user makes. A worker that fires at 3am has no such session. The fix was to generate and store the invoice PDF at the moment it's originally sent, not regenerate it on demand when a reminder later needs to attach it. It's a small architectural choice, but one of those constraints that only becomes obvious once you're building the unattended, scheduled half of a feature rather than the interactive half.

Rykkerflows sit alongside Welkent's broader move from a single-trade quoting tool into a full operations platform covering invoicing, materials, and job tracking across trades. Chasing payment is one part of running a trade business that shouldn't need a person to remember it.