Lehmora Labs is a software engineering studio based in Douala, Cameroon. For tontines and schools, our products record who owes what, since when, and who confirmed the payment. The money itself goes from payer to beneficiary, never through us.
Tontine des Amis de BonamoussadiCycle 3, Round 5 of 8
| Contributor | Confirmed | Received |
|---|---|---|
| Aïcha M. | 25 Oct | 25,000 |
| Brice N. | 26 Oct | 25,000 |
| Carine T. | 27 Oct | 25,000 |
| Didier E. | 29 Oct | 25,000 |
| Fabrice O. | 30 Oct | 25,000 |
| Grâce A. | 31 Oct | 25,000 |
| Hervé B. | unpaid | 0 |
Each payment is declared by the contributor, then confirmed by the beneficiary.
At a tontine in Douala, a single doubt about one contribution was enough to cause nearly two hours of tension. The group had been running for five years. Everyone wanted a better way to follow the money, but nobody wanted to hand that money to a new app.
People often assume you have to hold the money to manage it properly. For Tallyno, I chose the opposite direction: the engine never touches the money. It records commitments, tracks contributions and repayments, and keeps a verifiable trace of what happened.
That became the rule at Lehmora Labs: bring everyday financial habits online without becoming the intermediary that holds the money. Trust can come from a system that makes the rules and the movements verifiable.
In a tontine, the argument is never about the amount. It is about who paid, and when.
That is the one question our code must always be able to answer.
In Douala, the objection was never the technology: nobody wanted to hand the group’s money to an app. Tallyno starts from there, and Payskool applies the same principle to schools. Members pay the beneficiary over Mobile Money; families pay the school into its own merchant account. We keep the register: who owes what, since when, and who confirmed the payment.
To use Tallyno or Payskool, a member or a family never hands us their money. They only need to trust the register, which they can check.
With Tallyno and Payskool, money does not pass through our accounts. If the studio stopped, no group and no school would have funds to recover from us.
For these two products, no customer treasury to reconcile and no funds in transit to watch. Their cost stays that of software.
Funds held: none
Funds held: yes
Famsub is the exception, by choice: when people share subscriptions, the subscriber must be protected if the service is not delivered. So Famsub retains the amount for 30 days before releasing it to the owner, with a refund possible within 7 days of joining. Building that properly took a settlement queue, a double-entry ledger and refund logic: exactly the cost the other products avoid.
Each rule answers an argument any tontine member will recognise. It is enforced by code, not by the treasurer’s memory.
The argument. We’re starting a new cycle and he goes before us again, while he still owes us?
The rule. When a cycle is renewed and whenever rounds are reordered, a member in debt can never be placed before a member who is up to date.
assertDebtorsLast()The argument. My debt vanished when we restarted the cycle.
The rule. A debt is never deleted. It follows the debtor from one cycle to the next until it is paid or written off by the group.
carriedToGroupIdThe argument. She already got the pot. Why is she up again?
The rule. A member receives the pot only once per cycle. That is a uniqueness constraint in the database, not a manual check.
UNIQUE(tontineGroupId, beneficiaryId)The argument. The late fee was counted twice.
The rule. Late fees, an upcoming option, are recomputed from scratch every night, never incremented. A job that crashes and restarts doubles nothing.
penaltyAmountThe argument. Someone edited the previous cycle.
The rule. A completed cycle is immutable. Renewing it creates a new cycle; the old one stays exactly as it was closed.
status = COMPLETEDThe argument. A few francs went missing somewhere.
The rule. The pot is always share × number of contributors, in integers. There is no fraction of a CFA franc anywhere in the system.
cycleAmount * contributorCountThe argument. The app crashed halfway through the payout.
The rule. Every state change is written in a single transaction: the round, the expense and the event are recorded together, or not at all.
prisma.transaction()Taken from the 17 documented invariants of Tallyno’s tontine module.
Tallyno carries the studio’s thesis: the tontine, without anyone handing us their money. That is where the effort goes.
Tontines and group expenses.
| Product | What it does | Holds money? | Status |
|---|---|---|---|
| Famsub(opens in a new tab) | Peer-to-peer sharing of digital subscriptions, paid through escrow. | Yes. Retained 30 days before release, refundable within 7 days of joining. | In staging |
| Payskool(opens in a new tab) | School fee collection, for schools. | No. Families pay straight into the school’s merchant account. | In development |
Updated November 2026
No product is in production yet. Famsub runs in staging; Tallyno and Payskool are in development.
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