Guide
How to Sign an Invoice Online
Signed invoices create a stronger payment commitment than unsigned ones.
Steps
- 1
Create your invoice as markdown or PDF
- 2
Send to client for acknowledgement signature
- 3
Client receives signing link by email
- 4
Client signs to confirm payment terms
- 5
Both parties receive signed copy with audit trail
Try it with curl
curl -X POST https://signb.ee/api/send \
-H "Content-Type: application/json" \
-d '{
"content": "# Your Document\n\nContent here...",
"senderName": "Your Name",
"senderEmail": "you@email.com",
"recipientName": "Recipient",
"recipientEmail": "recipient@email.com"
}'Legal validity
Electronic signatures are legally binding under the ESIGN Act (US), eIDAS Regulation (EU), and Electronic Communications Act (UK). Every Signbee document includes a SHA-256 tamper-proof certificate.
More details
An unsigned invoice is a request. A signed invoice is a commitment. When a client signs an invoice, they're acknowledging the amount, payment terms, and deadline — creating a much stronger legal position if payment is disputed.
When to use signed invoices: - Large project milestones (>$5,000) - Net-30/60/90 payment terms - New client relationships without established trust - International invoices where payment disputes are harder to resolve - Invoices with specific acceptance criteria or conditions
What to include in a signed invoice: - Invoice number and date - Detailed description of goods/services delivered - Line item amounts and total - Payment terms (due date, accepted methods) - Late payment penalties - Bank details or payment link
For accounting automation: integrate invoice signing into your billing pipeline. When your accounting software generates an invoice, automatically send it for client signature via the API. The signed invoice becomes the authoritative record of what was owed and when.
Frequently asked questions
Why should I get invoices signed?
A signed invoice proves the client acknowledged and accepted the amount and payment terms. This is significantly stronger evidence in payment disputes than an unsigned invoice sent by email.
Can I automate invoice signing?
Yes. Use the API to send invoices for signature automatically when they're generated by your accounting software. The client signs electronically, and both parties receive the signed copy.
Related resources
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