For UK finance and procurement teams

Pay what you negotiated. Not a penny more.

Stemma stops suppliers overcharging you. Every invoice line is checked against your supplier agreements, POs and deliveries before it gets paid.

Six-week recovery audit at no cost. After that, a guaranteed 5x return.

Invoice
Read on arrival
01
Purchase order (PO)
Ordered quantity and price
02
Goods received note (GRN)
What actually arrived
03
Supplier agreement
Prices, rebates, terms
BEYOND 3-WAY
Stemma
Fuel surcharge overbilled
Haulage · 440 pallet deliveries
INVOICED
£20,650+£1,050
EXPECTED PER AGREEMENT
£19,600
STEMMA BUILD-UPAGREEMENT · RATE SCHEDULE
300 pallets × Zone 1 £35£10,500
140 pallets × Zone 2 £50£7,000
Fuel surcharge 12% (current band)£2,100
Fuel surcharge billed at 18%£3,150
Diesel index fell a band.
Surcharge stayed at the old rate.
OVERBILLED / MONTH+£1,050£12,600 a year
Technology built with support from
Innovate UK Techstars Plug and Play

1–2% of what you pay suppliers is overcharged.It passes every check and takes hours to find by hand.

Most invoices are only checked against a tolerance band, so an overcharge that fits inside it gets paid. Month after month.

Every supplier invoice checked against what you agreed.

Read-only access to your ERP. Stemma flags and drafts, your team decides.

What you pay suppliers
What customers pay you
Invoice line vs agreed price schedule
CheckAgreedInvoiceStatus
Product Box 400×300 Box 400×300
Volume tier Tier 3 (50k+) Tier 2 Mismatch
Unit price £0.38 £0.44 +15.8%
Quantity 62,000 62,000
Overcharge on this invoice
£3,720
Root cause
Lower volume tier billed
Evidence
Price schedule, tier table
Drafted next step
Request a credit note for the tier difference.

Works with your ERP.Reads whatever your suppliers send.

Read-only connection to your ERP, or any system that can export a file. No engineering work, and no change to how your team works.

Your systems Read-only by default.
50 · 200 · X3 · Intacct
Business Central · NAV
Cloud accounting
Oracle
Business One
Financials · Dimensions
Food & beverage
M3 · LN
Kinetic
+ 20 more ERPs and finance systems Anything else via CSV or Excel export
Your documents
XLSX
Statement 2026-07.xlsx
Supplier statement
READ
JPG
Scanned delivery note.jpg
Goods received
READ
EMAIL
Pasted from email
Statement table
READ
CSV
Rate card 2026.csv
Agreed prices
READ
PDF
Remittance Advice 2026-07.pdf
Customer remittance
READ

We find what you’ve overpaid. Then we stop it happening again.

Start free. Continue with a guaranteed 5x return.

01 · Recovery auditStart here
£0

Six weeks. We check your past invoices against your supplier agreements and show you what you’ve overpaid, with the evidence.

02 · Annual subscription
5xguaranteed return

Stemma checks every new invoice before you pay it. A fixed annual fee that we agree together after the audit, capped at 20% of what it finds, so every £1 you pay returns at least £5. No obligation to continue.

Read-only access to your ERPYour team sends every claimUK hosted, DPA with every customer
Start with a 20-minute call

Secure by default.

UK GDPR Article 28 DPA signed with every customer.

Request the security overview
Hosting
UK only
All customer data in Microsoft Azure UK South. AI processing in the EU. Nothing hosted in the US.
Sign-in
MFA on every account
Mandatory from the first sign-in, with no way to switch it off.
Access
Read-only by default
Nothing is written to your systems without your approval. No delete function exists.
Encryption
AES-256 at rest, TLS 1.2+ in transit
Secrets held in Azure Key Vault, never in code.
AI
Never trained on your data
One AI provider, inside our own Microsoft tenant. Zero data retention.
Backups
35-day point-in-time restore
Full restore drill completed in under 8 minutes.
Certification
Microsoft Azure
Hosting infrastructure, ISO 27001 and SOC 2
In place
Cyber Essentials
UK government-backed scheme
In progress · Oct 2026
Cyber Essentials Plus
Independently tested
In progress · Nov 2026
ISO 27001
Information security management
Planned · H1 2027

Founders with finance and AI research backgrounds.

Johannes Haug

Johannes Haug

CEO, Co-founderLinkedIn

Johannes worked in investment banking at Arma Partners and private equity at Triton Partners, where he saw portfolio companies overpay suppliers with no practical way to catch it. He graduated first in his class of 263 at BI Norwegian Business School, Norway’s top-ranked business school according to the Financial Times. He is a former Chess Olympian for Norway, a member of Team Magnus Carlsen and a Nordic Champion.

Devvrat Joshi

Devvrat Joshi

CTO, Co-founderLinkedIn

Devvrat was a founding software engineer at a £100m+ startup and has worked alongside the Google DeepMind team. He holds a Master’s in Intelligence and Machine Learning from Imperial College London, where he wrote the best master’s thesis, and a Bachelor’s from IIT Gandhinagar. He has published 9 papers at leading AI conferences.

Questions finance teams ask.

01

What access do you need, and who sets it up?

Read-only access to your ERP, or file exports if you’d rather not connect it. Your IT team approves the connection and we handle the rest.

02

How much of my team’s time does the audit take?

About two hours to go live, then a 20-minute weekly check-in to make sure everything runs smoothly on your side. Stemma does the checking.

03

What if the audit finds nothing?

You’ve paid nothing, and you have independent confirmation that your controls work. There’s no obligation to continue.

04

Will you contact my suppliers?

No. Stemma drafts each claim with its evidence, and your team decides what to send and when.

05

How is the subscription fee set?

We agree it together after the audit, based on what the audit found. It’s a fixed annual fee, capped at 20% of that value, so you get at least £5 back for every £1. Nothing is charged until we’ve both signed off on it.

Find out what you’re overpaying.

A 20-minute call with the founders. We show you what Stemma finds on a sample supplier agreement and estimate what you’re overpaying from your annual supplier spend. No documents needed.