Blood Components App summarises relevant national guidelines to act as a guide for clinicians to facilitate appropriate use of blood and enable robust documentation of indications. The App has been updated and is based on the National Blood Transfusion Committee (NBTC) Indication Codes for Transfusion (2020), the British Society of Haematology (BSH) Guideline on transfusion for foetuses, neonates and older children (2016) and The National Institute for Health and Care Excellence (NICE) Blood transfusion [NG24] guidelines . The App should be used in conjunction with the full guidelines.