Does Polygon offer dark pool data?

Yes, we do provide dark pool data. While we don't have an endpoint that specifically returns only dark pool trades, you can identify them using our Trades endpoint and our Trades WebSocket feed. Dark pool trades can be identified by their exchange ID of 4 (exchange:4) and the presence of an "trf_id" field. For example:

{ "conditions":[12,37], "exchange":4, "id":"1", "participant_timestamp":1642594169516358704, "price":170.28, "sequence_number":58452, "sip_timestamp":1642597200042949698, "size":62, "tape":3, "trf_id":201, "trf_timestamp":1642597200042608441 }