Our visual document editor lets you upload any PDF or DOCX and place signing fields exactly where they belong — no templates, no coding, no guesswork. The entire process takes under 3 minutes for standard documents.
Upload a PDF or DOCX file (max 50 MB) from your dashboard or via API.
DOCX files are automatically converted to PDF via LibreOffice headless mode (zero cost, no Microsoft dependency).
The document renders in a PDF.js canvas viewer at 2× resolution for pixel-perfect placement.
Drag signature, text, date, checkbox, or name fields from the sidebar onto any page.
Each field is assigned to a specific recipient — only that person can fill it.
Optionally mark fields as required — the signer cannot submit without completing them.
When ready, click 'Send for Signature' to create the envelope and dispatch email invitations.
File validation via Python python-magic (libmagic) — checks actual file magic bytes, not extensions.
UUID-based filenames prevent collision and enumeration attacks.
PDF.js renders at 150 DPI for precise visual field placement on all pages.
Field coordinates stored as relative percentages (page_x, page_y) — resolution-independent.
LibreOffice conversion runs in a sandboxed subprocess with 30-second timeout.
Signature (drawn or uploaded image), Text (single/multi-line), Date (auto-filled with timestamp), Checkbox (required acknowledgment), Name (auto-filled from recipient profile). Each field enforces type-specific validation at signing time.
When you upload a .docx file, IUSign invokes libreoffice --headless --convert-to pdf in a sandboxed subprocess. The resulting PDF is saved with a UUID filename. This eliminates the need for commercial DOCX libraries — it's fast, accurate, and costs nothing.
Each field is bound to a specific recipient by email. When a signer opens the document, only their assigned fields are editable. Other recipients' fields appear grayed out and locked. This prevents unauthorized modifications and ensures signing order integrity.
Create your free account and send your first document in under 3 minutes.
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