Smart Banner Hub Opens Clustrauth™ API — Quantum-Safe Document Signing for Developers at $5 Per Signature

Smart Banner Hub LLC today launched the Clustrauth™ API — a REST API that gives developers programmatic access to quantum-safe document authentication powered by the company's Clustrauth post-quantum authentication engine. Developers can now sign any file up to 50MB with hybrid Ed25519 + ML-DSA (NIST FIPS 204) cryptography and verify it forever — starting at $249 per month with 50 included signatures and unlimited free verification.

Until now, Clustrauth's quantum-safe signing was only available through Quantum Auth Forge™, Smart Banner Hub's consumer-facing authentication platform at $24.99 per document. The Clustrauth API brings the same NIST-approved cryptography to developers with predictable subscription pricing, enabling integration into any application, workflow, or document pipeline at a fraction of the per-document cost.

The API is designed for immediate integration. Developers authenticate with an API key, POST a file to the /sign endpoint, and receive a Certificate ID with full cryptographic proof. Verification requires only the original file and its Certificate ID — and it's free, forever.

• Quantum-safe dual signatures: Every document is signed with both Ed25519 (classical) and ML-DSA/CRYSTALS-Dilithium (post-quantum, NIST FIPS 204) — hybrid defense in depth
• SHA3-256 document hashing: Bit-level integrity verification across the entire file
• Certificate of Authenticity PDF: Programmatic access to a downloadable certificate for every signed document — proof developers can hand to their own customers
• Free unlimited verification: Verify any signed document against its Certificate ID at no cost, unlimited
• Permanent certificate storage: Every certificate is stored permanently and retrievable at any time
• Any file type up to 50MB: PDFs, contracts, images, code, medical records, legal documents — anything
• Multipart and base64 upload: Send files as form data or base64-encoded JSON — whatever fits the integration
• Idempotency keys: Built-in duplicate request protection — no double-charges on retries
• Tamper detection: Verification detects any modification to the original signed document
• Sandbox environment: Three free test signatures per sandbox key — full signing capability with no charge
• Usage dashboard & analytics: Real-time signature tracking, billing status, and estimated invoices in the Developer Dashboard

The Clustrauth API uses subscription billing — predictable monthly pricing with included signatures and transparent overage rates. No credits to manage, no prepayment required.

All plans include unlimited free verification, permanent certificate storage, Certificate of Authenticity PDF, API dashboard with usage analytics, and three free sandbox signatures per test key.

The Clustrauth API is available immediately. Developers can create API keys and start signing documents today at https://smartbannerhub.com/developer.

• Developer: $249/month — 50 signatures included, $5.00/overage
• Business: $999/month — 250 signatures included, $3.50/overage
• Enterprise: Custom — contact [email protected]
• Free unlimited verification on all plans
• Free sandbox with three test signatures per key
• Free Certificate of Authenticity PDF per signed document
• Free permanent certificate storage

Full API documentation, code examples, and sandbox access are available in the Developer Dashboard at https://smartbannerhub.com/developer

API keys work across both the Clustrolin animation API and the Clustrauth authentication API — one key, both engines.