Covo

Covo is a travel eSIM wallet: load money once, spend it on mobile data in 190+ countries at local rates, and never lose what you don't spend. No plan to expire, no bill shock when you land.

We built the product end to end on Open Mercato — the wallet, the billing, the eSIM lifecycle and the operator back office — plus the API behind the iOS and Android apps. Both are live in the stores.

The hard part isn't the eSIM, it's the money. “Never expires” means a balance has to stay correct indefinitely: held once in EUR cents, rendered in the traveler's own currency, charged the right VAT for the country it was topped up from, metered continuously as data burns down abroad, and still reconcilable against Stripe and the carrier — to the cent — years later.

Tech wrap-up

• Append-only wallet ledger held in EUR cents and rendered in the traveler's own currency — every balance on every screen is a replay of the ledger, not a stored number something can overwrite
• Stripe payments with per-country VAT, Apple Pay / Google Pay, saved methods, auto-refill, top-up bonuses and gift codes
• eSIM provisioning and pay-as-you-go metering over the carrier's provisioning API — webhook-driven and idempotent, so a retried carrier callback can't bill a wallet twice
• Family pooling with per-member spend caps, and kids' safety enforced on the network itself (content filtering, Safe Web) rather than on the handset
• Operator back office: consumers and wallets, invoices and refunds, country/zone pricing, bonus tiers, invite codes, and targeted push (APNs + FCM) with deep links
• Open Mercato backend: Next.js, MikroORM + PostgreSQL, Redis, Meilisearch