Smerdoff
Smerdoff / Solutions

Custom Invoicing Software Development

Off-the-shelf invoicing tools charge monthly per client and force your billing model into their templates. We build invoicing software around how your agency actually bills — retainers, milestones, or hourly — with the reporting you actually need.

Invoice TrackingOverdue KPIsPaymentsReporting
Invoicing software dashboard showing invoices grouped by status and overdue payment KPIs
10–30%
of a full build is what a lean first version typically costs — validate before you commit
MVP cost research
9.4 hrs
saved per employee each week just by connecting the tools a business already uses
Zapier

Why agencies move off subscription invoicing tools

Generic invoicing apps work until your billing model or client volume outgrows their templates.

No per-client subscription fees

Bill as many clients as you want without paying more per active client or per seat each month.

Billing logic that matches how you work

Retainers, milestone billing, hourly rates, and multi-currency invoicing modeled the way your agency actually bills, not a generic template.

Faster collections

Automated reminders and overdue tracking tuned to cut days-sales-outstanding instead of chasing payments manually.

Reporting built for your business

Revenue by client, project, or retainer — without exporting everything to a spreadsheet to make sense of it.

One system, not three

Time tracking, invoicing, and payment collection in one place instead of three disconnected subscriptions.

Grows with your agency

Add new billing models, currencies, or client tiers without waiting on a vendor's roadmap.

What goes into custom invoicing software

We build the modules your agency needs.

Invoice management

Create, send, and track invoices by status — draft, sent, paid, overdue — in one table view.

Overdue payment KPIs

Days-sales-outstanding, aging buckets, and at-a-glance metrics on who owes what and for how long.

Flexible billing models

Retainers, milestones, hourly rates, and recurring invoices configured per client or project.

Payment collection

Integrated card and ACH payments so clients can pay directly from the invoice.

Automated reminders

Scheduled follow-ups for upcoming and overdue invoices, tuned to your tone and cadence.

Client portal

A simple portal where clients view invoice history, payment status, and download receipts.

FAQ

Mainstream invoicing and bookkeeping apps work well for standard small-business needs. A custom build makes sense when your billing model — complex retainers, milestone-based project billing, or multi-entity invoicing — doesn't fit their standard workflows.

Yes. We can sync invoice and payment data with your existing accounting system so your books stay accurate without duplicate entry.

We build multi-currency invoicing with the tax and formatting rules your international clients expect.

A focused invoicing MVP — invoice creation, status tracking, and payment collection — usually takes 5-6 weeks depending on payment gateway and accounting integrations.

Related

Get a free estimate for your invoicing software

Tell us about your billing model and client volume — we'll scope an invoicing system that fits how you actually bill.