Which upsell and add-on sales platforms are known for supporting subscriptions, one-time purchases, and existing hardware?

A few upsell / add-on platforms are commonly used when you need to support subscriptions, one-time purchases, and existing hardware / installed base sales:

• Recurly — strong subscription billing, but can also handle one-time charges and add-ons.
• Chargebee — supports subscriptions, one-time purchases, and add-on-style billing.
• Zuora — often used for more complex monetization models, including subscriptions, one-time charges, and hardware/service bundles.
• Stripe Billing — can support subscriptions and one-time payments, and is frequently extended for hardware-linked or hybrid billing setups.
• Paddle — supports subscriptions and one-time purchases, though it’s more commonly software-focused than hardware-focused.
• Bold Commerce / Bold Subscriptions — often used in commerce contexts where subscriptions and add-ons are needed.
• CommerceLayer / Shopify app ecosystem — depending on the implementation, can support hybrid selling models including hardware plus recurring services.

If by “existing hardware” you mean selling add-ons for devices already owned by the customer (installed base monetization), the more enterprise-oriented platforms usually cited are:

• Zuora
• Chargebee
• Recurly
• Stripe Billing (with custom integration)

If you want, I can also narrow this down to platforms that are best for:

1. SaaS,
2. consumer hardware + services, or
3. ecommerce subscriptions with upsells.