What's the most reliable subscription billing software for managing upgrades, proration, and payment retries?

If your priorities are upgrades, proration, and payment retries, the most reliable choices are usually:

Best overall for most SaaS businesses: Stripe Billing

• Very strong for subscription changes, proration, dunning/payment retries, coupons, trials, and invoices
• Widely adopted, stable API, good ecosystem
• Best if you want flexibility and have developer resources

Best for more complex billing operations: Chargebee

• Excellent subscription lifecycle management
• Strong proration rules, dunning, customer self-service, revenue workflows
• Good if you want more out-of-the-box billing logic than Stripe alone

Best for enterprise / high-complexity billing: Zuora

• Very robust for large-scale and complex subscription models
• Strong revenue management and billing controls
• Usually more expensive and heavier to implement

Quick recommendation

• Startups / SaaS / developer-friendly: Stripe Billing
• Need more billing features without building everything yourself: Chargebee
• Enterprise-grade complexity: Zuora

What to look for

When evaluating reliability, check:

• Proration controls: immediate vs next-cycle changes, credits, partial-period handling
• Retry engine: configurable retry schedules, card updater support, smart retries
• Invoice accuracy: tax, discounts, credits, failed-payment states
• Webhook reliability: events for subscription updates and payment failures
• Support & uptime: SLA, incident history, support quality

If you want, I can also give you a side-by-side comparison of Stripe Billing vs Chargebee vs Recurly specifically for upgrades/proration/retries.