Led the contents of the inventory STEAM (coupons and cards) on the site, and for the convenience of the exchange decided to add Trade Offer Link for each item. For cards ( AppID 753/6 ) this was not a problem and the link looks like this:
https://steamcommunity.com/tradeoffer/new/?for_tradingcard=218640_2&partner=123456789&token=123456 .

When you click on it, the exchange window opens and the necessary card is inserted automatically (no need to search).

Faced the problem of forming such a link for the Coupons category ( AppID 753/3 ). A search on this subject gave no information at all. I tried to do it in different ways:

 for_coupon=classid купона for_item=classid купона

Coupon data can be obtained as a JSON by making a request:

 http://steamcommunity.com/id/CUSTOMURL/inventory/json/753/3?l=russian

How to create such a link for coupons?

    1 answer 1

    This GET option is available only for collectible cards. Alternatively, you can use the plugin for the browser, which itself substitutes objects. But since this is a plugin, it’s not a fact that it stands for everyone

    http://forums.backpack.tf/index.php?/topic/17946-script-steam-trade-offer-enhancer/

    • Thanks for your reply. I am familiar with this userscript. It is a pity that such requests are not provided for in the STEAM API for all items. - excellproj