Conversions API Payload Checker for Meta Event Match Quality

How to check what lowers Meta event match quality

Meta event match quality is a 0–10 score that Meta shows per event in Events Manager — see Meta's About event match quality page. Only Meta can calculate it. This checker reads the Conversions API payload your server sends and lists everything in it that Meta will reject or can't use for matching.

1. Copy a real payload. Take the JSON body from your server log, your CAPI gateway or tag manager, or a whole curl command. One event, an array of events or a full {"data":[…]} body all work.
2. Paste it above. The checks run as you paste. Choose a default country if your phone numbers have no country code.
3. Fix the red items first. Errors make Meta reject the event, and one bad event rejects the whole batch.
4. Then work on the yellow items. Missing high-priority keys, a private IP or a server user agent don't break the request, but they weaken matching.
5. Copy the corrected payload to see what your code should produce: values normalized and hashed, times in seconds, the right key names.

Meta's priority for match keys

Meta's help article ranks customer information parameters. High: email and click ID (fbc). Medium: Facebook Login ID, birthdate, country, phone, external ID and browser ID (fbp). Low: lead ID, first name, last name, city and zip code. Meta also says sending both IP address and user agent for all events may help matching. The table under the checks shows which of these each event sends.

What to do next in Events Manager

1. Fix your server code so it produces the corrected payload by itself — normalizing before hashing, sending event_time in seconds, and reading fbc and fbp from the visitor's cookies.
2. Send a test event. Copy the code from Events Manager › Data sources › your dataset › Test events, add it as test_event_code, and check that the event arrives with its parameters.
3. Remove test_event_code before going live, then wait. Meta scores the last 48 hours of events.
4. Read the score. In Events Manager, select your dataset, find the event and click View details to see its Event Match Quality and which parameters Meta received.

Common Conversions API payload errors

Meta conversions API user_data hashing mistakes

Plain-text email or phone values are not accepted. Hashing too early is just as bad: “US” hashed instead of “us” is a different value, and the hash of an empty string means the value was missing. The checker recognizes these hashes for country, gender and US states.

Meta CAPI phone number format

Digits only, with the country code and without leading zeros. A local number like 020 7946 0958 needs the country first: 442079460958. In “+44 (0)20 …” the (0) is dropped too.

Meta CAPI missing fbc

The click ID is one of the two high-priority keys, and Meta recommends sending it with every event. Read the _fbc cookie, or build fbc from the fbclid in the landing page URL — with a creation time in milliseconds, not seconds.

Client IP address and user agent

Meta wants the visitor's real IP address, unhashed, and website events can't be sent without a user agent. A 10.x or 192.168.x address is your network, not the shopper's, and “python-requests” or “axios” is your server, not their browser.

Meta CAPI deduplication and event_id

When the pixel and the server send the same purchase, Meta treats them as one event when event_name and event_id match. Meta asks for event_id on every event; an order number is a good choice.

event_time in milliseconds or older than 7 days

event_time is a Unix time in seconds (10 digits). A 13-digit value is milliseconds, and any event more than 7 days old makes Meta reject the whole request.