Refilr

What I built: Refilr is an onchain automated gas top-up platform built on Monad Testnet. Users deposit MON into a secure smart contract vault, register their operational wallets (trading bots, relayers, automation scripts), and configure refill policies per wallet threshold, refill amount, cooldown, and daily limit. An off-chain automation service continuously monitors wallet balances and submits refuel transactions when conditions are met. The contract independently validates every request before releasing funds. Users receive real-time Telegram alerts for every vault event refuels, deposits, withdrawals, pauses, and low runway warnings. What problem it solves: Operational wallets running out of native gas tokens is a silent, recurring failure for anyone running onchain automation on Monad. When a bot wallet hits zero, transactions stop, automation breaks, and you only find out after something has already gone wrong. Current solutions require constant manual monitoring and intervention. Refilr eliminates that entirely the vault enforces your rules onchain, the automation service never sleeps, and you get notified the moment anything happens. The key insight is that the automation key can only call refuel() it cannot withdraw funds, change policies, or register wallets. A compromised key cannot drain your vault faster than your own rules allow. The contract decides, not the bot. What I learnt: Building Refilr taught me how to architect a system where trust is enforced by code rather than assumed from a service. Separating the automation operator role from the owner role and making the contract the sole source of truth for every funding decision was the core design challenge. I learnt how to use viem and wagmi for real-time contract reads, event watching, and writes in a Next.js app, how to handle SSR hydration issues specific to wallet-connected frontends, and how to build a long-polling Telegram bot listener that runs alongside an automation service w