Checkout on a standard product cannot take a print file or a logo. A Shopify file upload form can. In SK Form Builder, the upload field uses an extension allowlist and checks type and size in the browser before the file is stored under a randomized name. The catalog does not publish a megabyte cap. Do not promise customers a maximum size you have not tested.
Use this form for print, engraving, and other made-to-order products when the file belongs with a request your team will price. If the file belongs on a quote that also hides the price, the quote app has its own upload. That upload attaches the file to the merchant email. It does not name CAD formats such as STL or STEP. This article does not treat the two uploads as one feature.
What belongs in the file field
Ask for the file the printer or engraver will open. A logo, a print-ready PDF, or a photo of the placement is enough for most stores. Ask for one file first. A repeater can add another guest or another block of fields. It is not documented as a multi-file gallery with a published file count.
- Extension allowlist: you decide which extensions the field accepts. Put that list in the label, in words shoppers use, such as PDF or PNG.
- Type and size checks: the browser validates type and size, and the server validates the submission again. No public number of megabytes is in the catalog.
- Randomized filename: the stored file name is not the shopper’s original name alone. Keep the original name in a text field if production staff need it.
- Media library: uploaded submission files can be reviewed in the app, with size information and bulk delete. Size information on a stored file is not the same as a published plan cap.
Runtime settings, including upload size limits, are loaded for the storefront from a restricted endpoint. Private keys are not in that payload. The existence of a size check is verified. The number you should print on the product page is not.
How to describe the field without a fake limit
Write the label as “Upload your logo (PDF or PNG)” if those are the extensions you allowed. SK Form Builder does not publish a megabyte cap, so leave any number off the label. If a test file fails, ask for a listed extension or a smaller file, then read the limit in the app before you add a number.
Conditional logic can hide the upload until the shopper chooses “I have artwork.” The rule operators are equals, contains, is empty, and greater or less than. A shopper who chooses “use your template” should not see a required upload they cannot complete.
Country, email, and product fields can sit beside the file. Email is required if you want the merchant notification’s reply-to to reach the buyer. The merchant email and an optional customer autoresponder both support merge tags. The file itself is part of the submission. Do not assume the autoresponder attaches the file. The catalog does not say that it does. The quote app does say customer-uploaded files are attached to the merchant email. That sentence is about the quote app, not this form.
Link the file to a draft order
A submission can create a Shopify draft order from product fields, and it can email a discount code. The product selection field uses Shopify’s resource picker so the draft points at a real product. Quantity uses the stepper.
Open the first draft order and the submission side by side. Confirm the product and quantity on the draft. Confirm the file on the submission in SK Form Builder. The catalog does not say the binary file is a line-item property on the draft order. Staff may need the submission, not only the draft, to download the artwork.
There is no card charge on the form. Staff price the draft and invoice from Shopify. If the buyer must negotiate, send them to the quote app instead of collecting a file and a hoped-for price in one textarea.
When the quote attachment is the better tool
Use the form upload when the shopper is requesting a custom product and your team will create a draft order. Use the quote form when the shopper is asking for a price on work that should not show a retail price, and the file is part of that request.
On Request a Quote and Hide Price, the quote form can include a file field. Uploaded files are attached to the merchant email and linked in the merchant and customer emails. The catalog does not name STL, STEP, or a size cap there either. A manufacturer who needs a named CAD workflow should test one file and should not advertise a format the app has not listed.
Do not install both uploads on the same product without a sentence that tells the buyer which one to use. Two upload buttons on one page produce two inboxes.
What to test before the product goes live
- Upload an allowed extension and confirm it appears on the submission and in the media library.
- Upload a blocked extension and confirm the form rejects it.
- Upload a file you consider large for your process. If it fails, do not publish a number you have not read in the app.
- Submit on a phone. The form is in a closed shadow DOM, so theme CSS will not restyle the control for you.
- If a draft order is enabled, confirm whether production can download the file without opening a second screen. Adjust the staff instructions to match what you see.
Spam controls still apply. A honeypot, an IP blocklist, and captcha do not scan the file for malware. The catalog does not describe virus scanning. Treat customer files as untrusted downloads.
Plan prices are Starter at no charge, Basic at $4.99 a month or $49.90 a year, and Pro at $12.99 a month or $129.90 a year. Storage is not split into published caps on those tiers in the catalog.
Questions about Shopify file upload forms
Is there a maximum file size?
The app checks size. The catalog does not publish a megabyte or gigabyte cap. Test a real file and read the limit in the app before you print a number.
Can the customer upload after checkout?
The order-paid survey can email a form after payment. You could place an upload on that form. The catalog does not describe a dedicated “upload after checkout” widget on the thank-you page. Test the email path if that is the workflow you want.
Will the form accept CAD files?
Only if you add those extensions to the allowlist and a test file succeeds. The catalog does not name STL or STEP. Do not advertise them as supported formats.
Add the upload in SK Form Builder for custom products your team will produce from a file. Install SK Form Builder after one allowed file and one blocked file behave the way your label describes.