ctSignature

1 Executive Summary

ctSignature is a B2B document signing platform that allows any business to add electronic signature capabilities to their existing products. Think of it as the engine behind the signing experience — businesses integrate via API or use our dashboard, and their customers sign documents through a secure, branded workflow.

Key Differentiators

• Self-service onboarding — Businesses sign up, get API keys, and start sending documents in minutes
• Embeddable signing — Businesses can iframe the signing experience into their own app
• Reusable templates — Upload once, send the same document to unlimited signers
• Comprehensive audit trail — Device fingerprint, IP, geolocation, timestamp, and document hash for every signature
• No per-seat pricing — Pricing is per document, not per user, making it predictable for businesses
• Real-time webhooks — Businesses get notified instantly when documents are signed, viewed, or expired

2 Platform Overview & Value Proposition

ctSignature serves as invisible infrastructure for other businesses. Their customers never need to know ctSignature exists — the signing experience lives inside the business's own product.

Who Uses ctSignature?

Platform Architecture (Simplified)

What a Business Gets

3 How It Works — End-to-End Flow

From document upload to signed PDF retrieval, here is the complete signing lifecycle.

Step 1: Create a Document

The business uploads a PDF and specifies the recipient. This can be done via the dashboard UI or the API.

Step 2: Place Signature Fields

The business (or their operator) opens the Placement URL in a browser. The PDF is displayed with a drag-and-drop interface for positioning:

• Signature box — where the signer draws/types their signature
• Printed name field — signer's full legal name
• Date/time stamp — automatically populated signing timestamp
• Digital audit stamp — IP, device info, and hash summary
• Initials fields — multiple initials boxes on any page (required or optional)

Fields are dragged, resized, and positioned on any page. When saved, the signing URL becomes active.

Step 3: Signer Receives the Link

The business sends the Signing URL to the signer (via email, SMS, in-app notification, etc.). No account is needed — the token in the URL grants access.

Step 4: Signer Signs the Document

The signer opens the URL and sees the PDF with highlighted signature areas. They:

1. Review the document in the in-browser PDF viewer
2. Choose a signature font or type their signature
3. Enter their printed name
4. Complete any required initials fields
5. Click "Sign Document"

Behind the scenes, the system captures a comprehensive device fingerprint including browser fingerprint, canvas fingerprint, screen resolution, timezone, language, platform, IP address, and optional geolocation.

Step 5: Signed PDF Generated

The signature, printed name, timestamp, and audit stamp are rendered directly into the PDF. A SHA-256 hash is computed and stored for tamper detection. The signer can immediately download the completed PDF.

Step 6: Business Notified

A webhook (document.signed) fires to the business's configured endpoint with the document ID and status. The business can then retrieve the signed PDF via the API.

4 Customer Dashboard — Complete Walkthrough

The dashboard is the web interface where business customers manage every aspect of their ctSignature account. It's accessed at /dashboard/ and requires email/password authentication.

4.1 Registration & Login

New businesses create an account by providing:

• Company name — displayed throughout the dashboard
• Email address — used for login and communications
• Password — minimum 8 characters, hashed with BCrypt

Upon registration, the account starts with a free trial of 3 document signings (configurable by platform admins). After using all trial documents, the business must choose a subscription plan to continue.

4.2 Overview Page

The home screen provides an at-a-glance summary:

• Stats cards — Total documents, Pending, Sent, Signed, Expired counts
• Trial banner — shows remaining trial documents (if on free trial)
• Quick actions — Send Document, API Keys, Account Settings shortcuts
• Recent documents — last 5 documents with status, recipient, and date

4.3 Documents Page

Full document management with two main areas:

Send Document Form

• Enter recipient name and email
• Upload a PDF file (max 10MB)
• Click "Create & Send" to generate the signing session
• A modal displays the Placement URL and Signing URL with copy buttons
• "Open Placement" button to immediately position signature fields

Document List

• Filterable by status (Pending, Sent, Signed, Expired)
• Paginated with configurable page size
• Click any document to open a detail modal showing:
  • Status, recipient info, creation and expiration dates
  • Clickable Placement and Signing URLs
  • Full signature audit trail (font, IP, location, platform, timestamp)
  • PDF integrity hash

4.4 API Keys Page

API keys are how businesses authenticate programmatic access. The page provides:

• Create key — enter an optional name (e.g., "Production", "Staging"), receive the full key once
• Key display format — ctds_live_aBcDeFg...xYz12345 (prefix + last 8 chars visible after creation)
• Key list — shows all keys with name, creation date, last used date, active/revoked status
• Revoke — instantly disable a key (with confirmation prompt)

4.5 Account Settings Page

• Company information — edit company name and email
• Password change — requires current password verification
• Account details — Account ID, current plan, trial usage, member-since date

4.6 Billing Page (Stripe-Powered)

• Current plan — active tier name, monthly price, document usage this period
• Usage progress bar — visual indicator of documents used vs. included
• Upgrade/downgrade — change plan via Stripe checkout
• Billing portal — access Stripe customer portal for invoices, payment methods, cancellation

5 API Integration Guide for Businesses

Businesses integrate ctSignature into their applications using our REST API. Authentication is via API key in the X-Api-Key header.

Authentication

Core API Endpoints

Template Endpoints

Webhook Endpoints

Example: Complete Integration in 4 API Calls

Rate Limits

6 Multi-Signer Workflows

Many business documents require more than one signature — contracts with two parties, approvals with multiple stakeholders, agreements involving buyers, sellers, and witnesses. ctSignature supports both sequential and parallel multi-signer workflows out of the box.

Workflow Types

How Multi-Signer Works

Key Features

• Per-signer tokens — each signer gets a unique, cryptographic URL; no shared access
• Per-signer field placement — each signer has their own signature box, printed name field, digital stamp, and initials fields on any page
• Signer roles — assign labels like "Buyer", "Seller", "Witness", "Guarantor" for clarity
• Progressive PDF rendering — in sequential mode, each signer sees the previous signers' signatures already on the document
• Individual audit trails — each signature event has its own full device fingerprint, IP, geolocation, and timestamp
• Co-signer progress — signers can see the status of other signers (completed, pending, waiting)
• Sequential gating — in sequential mode, signers are blocked with a clear message until it's their turn
• Single document count — a multi-signer document counts as one document for billing regardless of signer count

Common Use Cases

7 Document Templates & Reuse

Templates are the most powerful feature for businesses that send the same type of document repeatedly — contracts, NDAs, onboarding forms, consent documents, etc.

How Templates Work

Template Features

• Create from upload — Upload a fresh PDF, position fields, save as template
• Create from completed document — Turn any previously signed document into a reusable template
• Fixed field placements — Signature, printed name, date/time, digital stamp, and initials fields are saved at exact coordinates
• Unlimited sends — Each send creates a new independent document with its own tokens and audit trail
• Template management — List, edit, deactivate, and delete templates from the dashboard or API
• No re-placement needed — Send from template skips the placement step entirely

Use Cases

8 Security, Compliance & Audit Trail

Document signing requires trust. ctSignature implements multiple layers of security to ensure document integrity, signer identity verification, and comprehensive forensic audit trails.

Document Security

Signature Audit Trail

Every signature event captures the following data points for forensic verification:

API Security

• API key hashing — Keys stored as SHA-256 hashes, never in plaintext
• JWT authentication — Dashboard sessions use signed JWT tokens with 24-hour expiry
• Rate limiting — Per-tenant rate limits prevent abuse
• CORS restrictions — Configurable allowed origins per environment
• Security headers — X-Content-Type-Options, X-Frame-Options, CSP, HSTS, Referrer-Policy
• Webhook HMAC signing — Outbound webhooks are signed with HMAC-SHA256 so businesses can verify authenticity

Infrastructure Security

• HTTPS enforced in production via HSTS
• Database connections over TLS
• Passwords hashed with BCrypt (adaptive cost factor)
• No sensitive data in URL parameters (tokens are opaque, not JWTs)
• File storage isolated per tenant in separate directories

9 Pricing Tiers & Billing Model

ctSignature uses a hybrid pricing model: subscription tiers with included documents plus overage charges, and a pure pay-as-you-go option. All billing is powered by Stripe.

Free Trial

Subscription Tiers

Billing Mechanics

Tier Customization

All tiers are stored in the database and are fully admin-editable. Platform administrators can:

• Create new tiers with custom names, pricing, and document limits
• Modify existing tier pricing, overage rates, and included documents
• Enable/disable feature flags per tier (webhooks, templates, embedded signing)
• Deactivate tiers (prevents new subscriptions, existing subscribers are grandfathered)
• Adjust the free trial document limit globally

10 Webhook Notifications

Webhooks allow businesses to receive real-time HTTP notifications when events occur on their documents, eliminating the need to poll the API for status changes.

Supported Events

Webhook Payload Example

Security & Reliability

• HMAC-SHA256 signatures — every webhook includes a signature header so businesses can verify authenticity
• Automatic retries — failed deliveries retry 3 times with exponential backoff (1min, 5min, 30min)
• Delivery log — full history of webhook attempts, response codes, and retry status visible in dashboard
• Idempotency — each delivery includes a unique ID so businesses can deduplicate

Configuration

Businesses configure webhooks via the dashboard or API:

• Set the endpoint URL (HTTPS required in production)
• Choose which events to subscribe to
• Receive a signing secret for HMAC verification
• View delivery history and retry failed deliveries

11 Embedded Signing (White-Label)

Businesses can embed the ctSignature signing experience directly within their own application using an iframe, creating a seamless, branded experience for their end users.

How It Works

Embedded Signing Setup

1. Enable embedded signing in account settings
2. Add allowed domains (e.g., https://app.yourbusiness.com)
3. Embed the signing URL in an iframe:
   <iframe src="https://sign.ctsignature.com/sign/document/xyz789..." width="100%" height="800" frameborder="0" ></iframe>
4. Listen for completion via webhook or postMessage events

12 Technical Architecture

ctSignature is built on a modern, proven stack designed for reliability, security, and straightforward deployment.

Technology Stack

Multi-Tenancy Model

• Shared database, shared schema — all tenants share the same database tables
• Tenant isolation via query scoping — every query includes a WHERE tenant_id = ? clause
• Separate file storage — each tenant's PDFs are stored in isolated directories
• No global query filters — explicit scoping is used for safety and predictability

Database Schema (Key Tables)

Background Services

• Token Cleanup — runs hourly, nullifies tokens on expired unsigned documents
• Webhook Delivery — processes queued webhooks, handles retries with exponential backoff
• Usage Tracking — runs daily, processes overage billing at end of billing periods

13 Roadmap & Future Features

ctSignature is being built in phases. Here's where we are and where we're headed.

Current Status

Future Considerations

• Email notifications — optional built-in email delivery for signing links
• Bulk send — send a template to a CSV of recipients in one operation
• Custom branding — per-tenant logo and color scheme on signing pages
• Document attachments — attach supporting files alongside the main document
• Mobile SDKs — native iOS/Android SDKs for in-app signing
• SSO/SAML — enterprise single sign-on for dashboard access
• Advanced audit reports — downloadable compliance reports per document
• Document expiry reminders — automated email reminders before documents expire

Summary

ctSignature provides a complete, secure, and scalable document signing infrastructure that businesses can integrate into their products with minimal effort. With self-service onboarding, flexible pricing, comprehensive APIs, and enterprise-grade security, it's designed to be the signing engine that powers thousands of business workflows.