https://nostrel.com/blog Long technical pieces on M-Pesa, double-entry ledgers and the parts of payments that go wrong. en-KE Wed, 30 Sep 2026 00:00:00 GMT https://nostrel.com/blog/credit-on-a-callback https://nostrel.com/blog/credit-on-a-callback Safaricom does not sign its callbacks. What that means for every M-Pesa integration in Kenya, and why authenticating the endpoint is the smaller half. Wed, 30 Sep 2026 00:00:00 GMT support@nostrel.com (NOSTREL engineering) security https://nostrel.com/blog/integers-all-the-way-down https://nostrel.com/blog/integers-all-the-way-down 0.1 plus 0.2 is not 0.3, and in a payments ledger that is not a curiosity. What goes wrong, and the one rule that removes the whole class of bug. Sat, 12 Sep 2026 00:00:00 GMT support@nostrel.com (NOSTREL engineering) engineering https://nostrel.com/blog/the-2am-reconciliation https://nostrel.com/blog/the-2am-reconciliation The reconciliation problem from the point of view of the person who has to do it at month end, and why it is a bookkeeping problem rather than a payments one. Fri, 28 Aug 2026 00:00:00 GMT support@nostrel.com (NOSTREL) payments