What is a conversions API (CAPI)?
A conversions API sends conversion events from your server straight to an ad platform, alongside the browser pixel. Here is how it works, what Meta, TikTok, Snapchat and Google call their versions, an example, and common mistakes.
A conversions API is a server-to-server connection that sends conversion events, such as purchases, leads and sign-ups, from your website backend, app or CRM directly to an ad platform. It runs alongside the browser pixel, so the platform still receives events that ad blockers, browser limits or closed tabs stop the pixel from sending.
How does a conversions API work?
Your server sends each event with a name, a timestamp, an event ID and hashed customer details such as an email address. The platform matches the event to ad interactions. When the pixel sent the same event, the shared event ID lets the platform keep one copy. Each major platform has its own version:
| Platform | Server-side option | What its docs say |
|---|---|---|
| Meta | Conversions API (CAPI) | Use it "in addition to the Meta Pixel" |
| TikTok | Events API | Recommended with your existing Pixel |
| Snapchat | Conversions API | Send event_id on all events |
| Google Ads | Enhanced conversions | Sends hashed first-party data (SHA256) |
Sources: Meta's Conversions API best practices, TikTok's Events API overview, Snap's Conversions API guide and Google's enhanced conversions article.
Conversions API example
An illustrative UAE online store takes 1,000 orders in a month. Its pixel records 820 of them. The server sends all 1,000 with matching event IDs. The platform de-duplicates the 820 pairs and counts 1,000 purchases: not 820, which undercounts, and not 1,820, which double counts.
Common mistakes
- No shared event ID: pixel and server events are both counted.
- Batching late: Meta says "sharing events when they happen can help your campaigns achieve the best results."
- Ignoring consent: sending from a server does not change your obligations under laws such as Saudi PDPL and UK GDPR.
Related terms
See de-duplicated conversions and attribution window.
How Grower helps
Grower connects to Meta Ads, TikTok Ads, Snapchat Ads, Google Ads and 13 other channels and apps. Its attribution engine de-duplicates conversions from every channel into one count, so a sale two platforms both claim is counted once.
Frequently asked questions
Is the Conversions API the same as server-side tracking?
It is one form of it. Server-side tracking is the general practice of sending events from your server instead of, or as well as, the browser. A conversions API is the specific endpoint an ad platform provides to receive those events. Meta and Snapchat call theirs the Conversions API, while TikTok calls its version the Events API.
Do I still need the pixel if I use a conversions API?
Usually, yes. Meta's best practices say to use the Conversions API in addition to the Meta Pixel and share the same events through both. TikTok also recommends pairing its Events API with your existing Pixel. Running both gives the platform more complete data, as long as every event carries a shared event ID for deduplication.
Does a conversions API get around cookie consent?
No. Sending events from your server changes the delivery path, not the legal basis for using personal data. Where the law requires consent for advertising measurement, you still need it, whichever route the data takes. Hash customer identifiers before sending, and check each platform's terms and your local data protection rules.
See conversions from every connected platform on one de-duplicated count: book a Grower demo and we will connect a channel during the call.