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Capture
Invoices from email, PDFs, and phone photos land in one queue.
For US commercial general contractors
Never pay a sub twice.
Unstack checks every subcontractor invoice against the contract and the lien waiver, before the money leaves.
Founding pilot now open · Limited spots
Illustrative demo: a pile of subcontractor invoices is scanned. Clean invoices post to a ledger, two go to a review tray, and one missing lien waiver is requested from the subcontractor automatically.
Unstack in 90 seconds
Illustrative example
The $84,000 mistake
- You approve a sub's invoice.
- You pay it.
- They don't pay their supplier.
- A lien lands on the building. You pay again.
The waiver was missing. Nobody checked.
How it works
Four checks. Zero chasing.
Lien waivers
Every waiver. Every pay app. One screen.
Conditional, unconditional, progress, final. Tracked per sub, per payment.
Illustrative demo: a grid of six subcontractors by five pay applications, showing each lien waiver as received, requested, missing or not yet due. Missing waivers are requested automatically.
Subcontractor risk score
Know who's risky before you pay.
Illustrative demo · Tap a card to see why
Features
Everything AP was doing by hand.
Reads any invoice
Email, PDF, or photo. No retyping.
Contract check
Catches overbilling against the schedule of values.
Lien waiver tracking
The right waiver, for the right payment.
Auto-chase
Subs get reminded until the waiver arrives.
Duplicate & math check
Same invoice twice? Totals don't add up? Flagged.
Risk score
Green, amber, red for every sub.
One-click approve
Your team reviews only what's flagged.
Posts to your books
Clean invoices go straight into accounting.
Faster month-end close
Nothing stuck in someone's inbox.
Built for your team
One tool. Three people who sleep better.
Close the books faster.
- Clean invoices post themselves
- Exceptions in one queue
- Nothing lost in inboxes
Stop chasing waivers.
- Auto-reminders to subs
- Every waiver in one grid
- No more spreadsheet tracking
Never pay twice.
- No payment without the right waiver
- Risky subs flagged early
- Fewer lien surprises
The AP queue
Your AP inbox, finally sorted.
Illustrative demo: an accounts payable dashboard. New invoices arrive, are scanned, and either post automatically or are flagged for review with a one-click approve button.
Time-back estimator
How many hours is AP losing?
Hours saved per month100
Hours saved per year1,200
Approx. labor cost saved per year$54,000
Estimate assumes 12 min manual vs 2 min with Unstack per invoice, at $45/hr loaded cost. Not a quote or guarantee. Doesn't include the cost of a double payment.
Check this against our real numbersFounding pilot: 5 US general contractors.
Work directly with the founder. Shape the product. Pilot terms on the call.
Apply for a pilot spotFAQ
Questions, answered.
No. It sits in front of it, checking invoices before they're posted and paid.
Conditional and unconditional, progress and final. Several states use their own statutory waiver forms, and Unstack is set up to track the form your state requires.
No. They keep emailing invoices like they do today. Waiver reminders reach them by email.
Most pilots are running within a few weeks.
We'll walk through exactly how your data is handled on the call.
US commercial general contractors, roughly $20M–$100M in annual revenue, with a controller or AP team handling sub invoices.
Pricing is set during the pilot conversation.