create_upload_url

Get a short-lived URL to upload a PDF that GoodSign will turn into a document. Use this for a document that is NOT based on an existing GoodSign template — e.g. a Statement of Work, contract or NDA drafted for this specific deal. After the PUT succeeds, call create_document_from_upload with the upload_id this returns. The URL is valid for 15 minutes.

If you are GENERATING the PDF yourself, embed text tags where fields should go — GoodSign places a real field at each tag's exact position, and each distinct KEY becomes one signer (reuse the same KEY on every tag that person fills).

TAG REFERENCE — this is the complete list; any other tag type is discarded:

• [sign|KEY] signature. [in|KEY] initials. Signature size variants: [signxs|KEY] [signsm|KEY] [signmd|KEY] [signlg|KEY] [signxl|KEY].
• [date|KEY] date of signing, filled in automatically.
• [input|KEY] required text box. [input?|KEY] optional text box. [input|KEY|Some text] pre-filled, signer can edit.
• [name|KEY] and [email|KEY] text boxes pre-filled with that signer's name / email address.
• [c|KEY|Label] optional checkbox. [c*|KEY|Label] required checkbox. [c|KEY|x Label] pre-checked. [c1|KEY|Red] [c1|KEY|Blue] = radio group (same digit = one group, signer picks one).

RULES — breaking any of these corrupts or silently drops fields:

1. KEY is the signer key: letters and digits ONLY (Client, signer1), identical spelling and case on every tag for that person. Keys differing only in case, spaces or punctuation collide into the wrong signer. Exception: trailing padding spaces before the closing ] (rule 4) are stripped before the key is matched, so [name|Client ] still keys to Client.
2. A tag must be one unbroken run of selectable text on a single line in a normal font — never an image, never wrapped across lines.
3. Do not use square brackets anywhere else in the document — prose like "[insert date]" gets parsed as a tag. Use parentheses instead.
4. The tag's printed size becomes the field's size: its font size sets the field height, and an input/name/email box is exactly as wide as the printed tag text — write the tag at the size you want the answer to be. To WIDEN an input/name/email field without making it taller, pad with trailing spaces INSIDE the tag before the ] — e.g. [name|Client ] — the spaces count toward the printed width but are stripped from KEY. Spaces after the ] do nothing. Print the tag in a monospace font (e.g. Courier) so each padding space adds a full, predictable character width.
5. Leave 2-3 blank lines of clear space around sign/in tags: the drawn signature renders much larger than the tag text.

GoodSign erases the tag text from the final PDF and renders the field value in its place. After create_document_from_upload, confirm with get_document that the signer keys and field count match what you embedded.