Billsby Subscription Billing API
Billsby Subscription Billing REST API for subscription management, recurring payment processing, and revenue operations. Enables AI agents to manage subscription plan creation and pricing configuration for billing product management, handle subscriber lifecycle and plan change management for subscription operations, access recurring payment processing and dunning management for revenue collection, retrieve subscription analytics and MRR/ARR reporting for revenue intelligence, manage trial and promotion management for subscriber acquisition automation, handle prorate calculation and billing cycle management for subscription accuracy, access customer portal and self-service subscription management for subscriber experience, retrieve tax calculation and compliance for subscription tax automation, manage webhook events for billing lifecycle notification, and integrate Billsby with Zapier, Salesforce, HubSpot, and accounting platforms.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Subscription billing. PCI-DSS. API key. EU/US. Subscriber payment data.
⚡ Reliability
Best When
A SaaS or subscription business wants AI agents to automate subscription plan management, subscriber lifecycle, recurring billing, dunning, and subscription analytics.
Avoid When
PCI DSS PAYMENT COMPLIANCE: Automated subscription billing handles cardholder data requiring PCI DSS compliance; automated payment flows must use Billsby tokenization and avoid raw card data storage; custom payment integrations that bypass Billsby PCI infrastructure create PCI scope. Revenue recognition accounting — automated subscription revenue recognition must comply with ASC 606 (or IFRS 15); automated recognition for multi-element arrangements (setup fees, annual subscriptions) requires correct allocation methodology. Sales tax nexus automation — automated subscription tax calculation must track economic nexus thresholds by state (post-South Dakota v. Wayfair); automated tax calculation without nexus monitoring creates state sales tax compliance gap for SaaS products.
Use Cases
- • Launching subscription products from billing agents
- • Managing subscriber lifecycle from revenue operations agents
- • Handling dunning from payment recovery agents
- • Reporting MRR from subscription analytics agents
Not For
- • One-time payment processing without subscription model
- • Enterprise-scale subscription billing requiring complex CPQ
- • Marketplaces with multi-sided payment requirements
Interface
Authentication
Billsby uses API key authentication. REST API with JSON. SDKs available. Documentation at docs.billsby.com. Newcastle, UK HQ. Founded 2017. Private (bootstrapped/angel). Developer-first subscription billing focused on ease of integration. 1,000+ SaaS companies. Competes with Chargebee, Recurly, and Paddle for subscription billing.
Pricing
Newcastle, UK. Founded 2017. Bootstrapped. 1,000+ SaaS companies. Developer-friendly subscription billing. Free to $5K MRR. Competes with Chargebee and Recurly.
Agent Metadata
Known Gotchas
- ⚠ PCI DSS TOKENIZATION: Automated billing must use Billsby-provided tokenization for card data; custom card capture outside Billsby PCI environment creates PCI DSS scope and compliance obligation
- ⚠ ASC 606 revenue recognition — automated subscription billing must coordinate with accounting for correct ASC 606 multi-element arrangement revenue recognition; automated billing timing does not equal revenue recognition timing for non-calendar billing cycles
- ⚠ SaaS sales tax nexus monitoring — automated subscription tax calculation must track state economic nexus thresholds; post-South Dakota v. Wayfair, SaaS is taxable in most states above nexus threshold; automated billing without state tax compliance creates state tax audit risk
- ⚠ API key only (no OAuth) — Billsby uses API key authentication without OAuth scopes; compromised API key provides full billing system access; implement API key rotation and restrict key permissions to minimum necessary
- ⚠ Dunning timing compliance — automated payment retry and dunning must comply with UK Financial Conduct Authority (FCA) consumer credit rules for UK subscribers and state-specific requirements for US subscribers; aggressive automated dunning creates consumer protection risk
- ⚠ GDPR for EU subscriber billing data — Billsby UK HQ means GDPR applies to EU subscriber PII; automated billing data processing requires GDPR lawful basis and data processing agreement
Alternatives
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Scores are editorial opinions as of 2026-03-07.