Outbrain's help page recommends utm_source=Outbrain&utm_medium=Discovery, set in the campaign's Tracking section. Copy it as written and GA4 finds no channel for those clicks, because Discovery isn't a medium any GA4 rule recognises. Keep Outbrain's macros and change two things: a lowercase source, and a paid medium, cpc.
The interactive UTM builder loads with this page, pre-filled for Outbrain, and runs entirely in your browser.
A medium of cpc counts as paid in GA4, and with outbrain absent from Google's source lists that sends the click to Paid Other instead of Unassigned. campaign_name is listed for the tracking code in Outbrain's macro table.
Where to put it
Open the campaign's settings with the pencil icon, find the Tracking section, paste the string and click Submit. Outbrain appends it to every ad in the campaign.
Don't add UTMs to the URL you submit as content; Outbrain says the Tracking section is the only place for them.
Write macros as {{macro}} or [macro], and put a separator between two macros side by side, such as {{publisher_name}}_{{section_name}}.
Keep question marks, @ signs and repeated # out of the suffix, and don't end the submitted URL with a slash.
Macros filled in at click time
Macro
Resolves to
{{campaign_name}}
Campaign name
{{campaign_id}}
Campaign ID
{{ad_id}}
Ad ID
{{ad_title}}
Ad title (the headline)
{{ad_name}}
Ad name
{{publisher_name}}
Publisher the ad appeared on
{{publisher_id}}
Publisher ID
{{section_name}}
Publisher section name
{{section_id}}
Publisher section ID
{{doc_title}}
Title of the promoted content
{{time_stamp}}
Timestamp
{{ob_click_id}}
Click ID for server-to-server conversions
{{cpc}}
Cost per click in USD
Outbrain's own help page spells the source two ways. The recommended tracking code says utm_source=Outbrain with a capital O, and the best-practice list further down says always use utm_source=outbrain. GA4 treats parameter values as case sensitive, so a team that copies from both parts of the page gets two Outbrain rows in its source report. Pick lowercase and use it on every campaign.
Why Discovery finds no channel. GA4's paid channels need a medium that contains cp, is ppc or retargeting, or starts with paid. Discovery is none of those, and it isn't social, email, referral or any other medium a GA4 rule names. With a source that isn't on Google's lists either, the click matches nothing and GA4 calls it Unassigned. utm_medium=cpc puts it in Paid Other, where GA4 keeps ad clicks from networks it doesn't classify. If you want the word discovery somewhere, put it in utm_campaign.
Outbrain's code puts a section ID in utm_id. The recommended string ends utm_id={{section_id}}. GA4 defines utm_id as the campaign ID, the same ID you use when uploading campaign data. If you import cost or campaign data, a publisher section ID in that slot won't match anything you upload. Move the section to utm_content and keep utm_id for {{campaign_id}}. The utm_id decoder explains what GA4 does with the parameter.
Check the column before you add a macro. Outbrain's macro table has separate columns for the tracking code, click pixels and impression pixels. {{campaign_name}} and {{ob_click_id}} are marked for the tracking code only, while cid, pc_id and did are click-pixel macros that won't fill in a UTM. For publisher detail, Outbrain pairs two macros, utm_term={{publisher_name}}_{{section_name}}, and says two macros used together always need a separator between them.
Mind the trailing slash. Outbrain advises against ending the URL you submit with a slash, which its page calls a backslash, because it can cause reporting issues when used with UTM parameters. Paste the finished landing page URL into the redirect checker to confirm where it resolves before you submit it.
Questions
What is the Outbrain click ID?
{{ob_click_id}}, which Outbrain's macro table describes as a server-to-server multiple conversion ID. It's listed for the tracking code, so you add it as its own parameter, named whatever your conversion system expects, in the campaign's Tracking section.
Should I use utm_medium=discovery for Outbrain in GA4?
Not if you want the clicks in a channel. Discovery matches none of GA4's channel rules, so with an outbrain source the clicks report as Unassigned. Switch to cpc and they report as Paid Other.
Where do I add UTM parameters in Outbrain?
In the campaign's Tracking section, reached with the pencil icon on the campaign. Outbrain appends that code to every ad in the campaign and says not to add UTMs to the content URL itself.