Validation, conditional fields and formulas

Catch bad data as it's typed, show fields only when relevant, and calculate totals.

Validation

A text field can enforce a format as the signer types:

email, phone, number, date
PAN, GST and Aadhaar formats
a character limit
a custom pattern for anything else

Invalid input is flagged immediately, in the signer's language, rather than being discovered a week later.

Conditional fields

A field can depend on another. Show the "reason for exemption" text box only when the "claiming exemption" checkbox is ticked. Hidden fields aren't required and aren't sent, so nobody is blocked by a question that doesn't apply to them.

Formula fields

A formula field calculates from other fields on the same envelope. Reference other fields by their label and use the usual arithmetic:

{quantity} * {unit_price}
{subtotal} * 0.18
{subtotal} + {gst}

The result updates live as the signer types, and is flattened into the final PDF as a value like any other field. Useful for order forms, invoices and anything with a total the signer should see before committing.

Formula fields are calculated in the signer's browser and re-checked on the server before the document is sealed, so a manipulated browser can't produce a document with a wrong total.

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More in Fields & forms

Every field type, and when to use itAll fifteen field types explained, with the rules each one enforces. Anchor tags — place fields by writing them into the documentPut a marker like {{sign:1}} in your template and the field lands there automatically. Collecting payment at signatureTake money by UPI or Razorpay as part of the signing ceremony.