Server-side events · Platform reference

Meta Conversions API checker

The Meta Conversions API lets your server POST web, app, offline and messaging events straight to a Meta Pixel (dataset) ID, alongside or instead of the browser Pixel. Events usually show as received but go unattributed because of weak or wrongly formatted customer information (hashed fbc/fbp, missing IP or user agent, phone without country code), an event_time more than 7 days old, or an event_id that doesn't match the Pixel's eventID.

Read from the official documentation on 9 November 2026. Sources are listed at the end.

Check your own setup

Paste a Meta CAPI JSON payload and the checker flags the problems above: fbc/fbp format (and whether they were hashed), event_time older than 7 days, a missing or invalid action_source, unhashed contact fields, a missing event_id for dedup, and Purchase without value/currency. It can't see your Pixel, so it can't confirm that the browser eventID really matches.

Open the Meta CAPI Event Checker

Endpoint and authentication

POST https://graph.facebook.com/{API_VERSION}/{PIXEL_ID}/events

access_token query parameter carrying the Conversions API access token you generate for the Pixel/dataset

Standard event names

Spelled exactly as Meta expects them. A near miss is treated as a different event.

Event	Use it for
Purchase	the only standard event Meta marks as requiring value and currency
Lead	lead or form submission
CompleteRegistration	sign-up completed
InitiateCheckout	checkout started; value and currency optional
AddToCart	value and currency optional
AddPaymentInfo	payment details added
ViewContent	key page or product view
Subscribe	paid subscription started
StartTrial	free trial started
Contact	contact made (call, SMS, email, chat)
Schedule	appointment booked
SubmitApplication	application submitted
Search	site search
AddToWishlist	wishlist add
CustomizeProduct	product customised
Donate	donation
FindLocation	store locator use

Required and recommended fields

Field	What it needs
event_name	Required. Standard or custom event name; it is also half of the dedup key
event_time	Required. Unix timestamp in seconds; at most 7 days in the past
user_data	Required. Customer information object (see matchKeys)
action_source	Required. One of email, website, app, phone_call, chat, physical_store, system_generated, business_messaging, other. Meta says that by using the API you agree the value is accurate
event_source_url	Marked optional, but required for website events sent through the Conversions API
user_data.client_user_agent	Required for website events; not hashed; must be set manually for server events
event_id	Optional but recommended for deduplication; Meta recommends sending it (and external_id) on all events
custom_data.value + custom_data.currency	Required for Purchase
data_processing_options	Optional; if you send LDU, data_processing_options_country is required

Match keys and hashing

Key	Normalise and hash
em	SHA-256 required. Trim leading and trailing spaces and lowercase first
ph	SHA-256 required. Remove symbols, letters and leading zeros; always include the country code, e.g. (650)555-1212 becomes 16505551212
fn / ln	SHA-256 required. Lowercase, no punctuation; special characters UTF-8 encoded
db	SHA-256 required. YYYYMMDD, e.g. 19970216
ge	SHA-256 required. f or m
ct	SHA-256 required. Lowercase, no punctuation, no special characters, no spaces (newyork)
st	SHA-256 required. US: lowercase 2-letter ANSI code (ca); elsewhere lowercase with no punctuation, special characters or spaces
zp	SHA-256 required. Lowercase, no spaces or dashes; US first 5 digits only; UK area+district+sector (m11ae)
country	SHA-256 required. Lowercase ISO 3166-1 alpha-2 (us)
external_id	SHA-256 recommended, not required. Any unique advertiser ID
client_ip_address	Never hash. Valid IPv4 or IPv6, no spaces
client_user_agent	Do not hash
fbc	Do not hash
fbp	Do not hash
lead_id	Do not hash. Integer ID from Meta Lead Ads

Click ids

Click id	Where it comes from
fbc	From the _fbc cookie. Format fb.${subdomain_index}.${creation_time}.${fbclid}, e.g. fb.1.1554763741205.AbCdEf...; send it unhashed in user_data
fbp	Browser ID from the _fbp cookie. Format fb.${subdomain_index}.${creation_time}.${random_number}, e.g. fb.1.1596403881668.1116446470; unhashed
ctwa_clid	Click-to-WhatsApp click ID; do not hash

Deduplication

Recommended method: the Pixel's eventID must equal the server event_id, and the Pixel's event must equal event_name.
Window: events are deduplicated only if received within 48 hours of the first event with that event_id; Meta generally keeps the first one received.
If a browser and a server event arrive at about the same time (within 5 minutes), the browser/app event is favoured.
Alternative method: event_name plus fbp and/or external_id. This only works when the browser event arrives first; server events are not discarded if no browser event arrived in the prior 48 hours.
An order number or transaction ID makes a good event_id. Otherwise generate a random one and send the same value from browser and server.
Retrying is fine: if the same event_id and event_name arrive more than once, only the first copy is kept.

Time limits and batch sizes

event_time is Unix seconds and can be up to 7 days before you send the event.
If any event_time in data is more than 7 days in the past, Meta returns an error for the entire request and processes none of its events.
Up to 1,000 events per request in the data array.
Offline/physical store transactions: upload within 62 days of the conversion.
Meta recommends sending events in real time or in batches close to real time. You should be able to verify events about 20 minutes after you start sending.

How to test before you trust it

Test Events tool (Events Manager): Copy the generated test ID and send it as test_event_code in the payload. Remove it before sending production payloads.
Payload Helper: Fill in the required and recommended fields to see how your payload should be structured before your server sends it.
Event Match Quality: In Events Manager, each server event gets a score out of 10 showing how well its customer information can match to a Meta account. Web events only.
Events Manager overview: Shows the number of raw, matched and attributed events received.

Why events arrive but don't attribute

fbc or fbp sent hashed. Meta says not to hash them, so a hashed value can't be matched to the click. Read them from the _fbc and _fbp cookies, send them as-is, and refresh them regularly.
A single stale event sinks the batch: if any event_time is more than 7 days old, the whole request is rejected and none of its events are processed.
Pixel eventID and server event_id differ (or the Pixel event and server event_name differ), so the pair isn't deduplicated and Purchase is double-counted. Duplicates arriving more than 48 hours apart are never merged.
Website events with no client_user_agent or event_source_url. Both are required for website events, and client_ip_address has to be added manually on the server.
Contact information (email, phone, name) sent unhashed. Meta's systems are designed not to accept it.
Phone numbers without a country code, or with leading zeros, hash to a different value and won't match. Meta says to always include the country code.
Purchase sent without value and currency. Both are required for Purchase, so there is no value for ROAS reporting.
test_event_code left in production code. Meta says to remove it from production payloads.

Sources

Platforms change these rules without notice. If a source says something different from this page, the source wins.

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