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API Tools

Prefill Link API

This API allows you to generate a URL that prefills all or part of a new label form. The simplest way to generate a prefill URL is to use our prefill link builder tool. Developers who want to generate Stampnik URLs within their applications can refer to the following available prefill options.

Prefill links should use this base URL (https://stampnik.com/prefill?) and all params should be appended to the URL. All parameters are optional and are used to prefill a user-editable label form. No API key is required.

Prefill Link Params

Parameter Required Type Description
service No string Selects which carrier and service level to use. Here's a list of available service levels.
from_name
to_name
No string Sets the "Name" field of the From/To address.
from_street1
to_street1
No string Sets the "Street" field of the From/To address.
from_street2
to_street2
No string Sets the "Apt/Suite" field of the From/To address.
from_city
to_city
No string Sets the "City" field of the From/To address.
from_region
to_region
No string Sets the "State" field of the From/To address.
from_postcode
to_postcode
No string Sets the "Zipcode" field of the From/To address.
from_phone No string Sets the "Phone" field of the From address.
from_country
to_country
No string
(ISO 2-letter country code)
Sets the "Country" field of the From/To address. Only US is supported for now.
note No string Sets an optional 'note' to be printed on the label (up to 100 chars)
redirect No string (url) Sets the redirect link shown when a label is purchased. We append a GET param to your redirect link that includes the tracking numbers (e.g. "http://mystore.com/order/12345?tracking_numbers=USPS+123456789012) Note: only one redirect link is saved per cart order.
package No string Selects the package type. Choose from available flat-rate packages or use custom_box to define a custom package.
If package is set to custom_box, the following params define package size and weight
package_width No number Set the package width (in inches).
package_height No number Set the package height (in inches).
package_length No number Set the package length (in inches).
package_weight_lb No number Set the package weight (in pounds). Both weight values are added together to determine total weight.
package_weight_oz No number Set the package weight (in ounces). Both weight values are added together to determine total weight.

Prefill Link Examples

Here are some example use cases and URLs that you can create with the Prefill API

Use case Example URL
Preselect USPS Express Mail https://stampnik.com/prefill?
    &service=usps_express
Send a flat-rate envelope from ABC Example Co. https://stampnik.com/prefill?
    &from_name=ABC+Example+Co
    &from_street1=999+Main+St
    &from_street2=
    &from_city=Jacksonville
    &from_region=FL
    &from_postcode=32099
    &from_country=US
    &service=usps_priority
    &package=usps_flat_rate_envelope
Send a Custom Box (10" x 10" x 6", 15 ounces)
via USPS Ground Advantage
with note "Order No. 12345"
https://stampnik.com/prefill?
    &service=usps_ground_advantage
    &package=custom_box
    &package_weight_lb=
    &package_weight_oz=15
    &package_width=10
    &package_height=10
    &package_length=6
    &note=Order+No.+12345

Pre-defined Values

Use these values to select a flat-rate package and/or service level.

Service Levels

Value Description
usps_priority USPS Priority
usps_express USPS Express
usps_ground_advantage USPS Ground Advantage
usps_media USPS Media Mail
usps_first USPS First-Class Deprecated: This service is no longer offered by USPS. If used, it will re-map to Ground Advantage
usps_parcel_select USPS Parcel Select Deprecated: This service is no longer offered by USPS. If used, it will re-map to Ground Advantage

Flat-Rate Packages

Value Carrier & Service Description
usps_flat_rate_box_small USPS - Priority
Box
Small
usps_flat_rate_box_medium USPS - Priority
Box
Medium
usps_flat_rate_box_large USPS - Priority
Box
Large
usps_flat_rate_box_large_board_game USPS - Priority
Box
Large Board Game
usps_flat_rate_envelope USPS - Priority
Envelope
Letter
usps_flat_rate_envelope_legal USPS - Priority
Envelope
Legal
usps_flat_rate_envelope_padded USPS - Priority
Envelope
Padded
usps_flat_rate_envelope_small USPS - Priority
Envelope
Small
usps_flat_rate_envelope_window USPS - Priority
Envelope
Window
usps_flat_rate_envelope_giftcard USPS - Priority
Envelope
Gift-card
usps_flat_rate_express_envelope USPS - Express
Express Envelope
Letter
usps_flat_rate_express_envelope_legal USPS - Express
Express Envelope
Legal
usps_flat_rate_express_envelope_padded USPS - Express
Express Envelope
Padded