OneSignal

Start with OneSignal's free plan and focus on mobile push where the value is unlimited. For web push, keep your subscriber base under the 10,000 cap per send — segment early and often, but remember you're limited to 6 segments, so structure them around high-intent actions (e.g., cart abandoners, feature adopters) rather than vanity metrics. Use your 10,000 monthly email sends for transactional messages (order confirmations, password resets) instead of marketing blasts, since that budget goes fast. With only 1 active in-app message, rotate campaigns weekly and A/B test one element at a time. OneSignal handles FCM/APNs under the hood, so you get native push delivery without managing platform SDKs separately — a huge time saver for indie hackers. Check the pricing page for upgrade costs as you approach the web push cap.