For the moments when your body has decided there is an emergency and your head knows there is not one. Nothing here needs signing up to, nothing is recorded, and it works offline once the page is open.
Use this when breathing alone is not enough, or when the panic is about a thought rather than a feeling. It works by pulling attention back into the room, which competes with the loop in your head.
A panic attack is an adrenaline surge with no threat to spend it on. Racing heart, tight chest, tingling hands, a feeling of unreality, the conviction that something terrible is about to happen — these are all what adrenaline does. It peaks within about ten minutes and then falls. It is extremely unpleasant and it is not dangerous, and knowing that is part of why these techniques work.
Slow, long exhales work because they raise the tone of the vagus nerve, which tells your heart to slow down. The exhale needs to be longer than the inhale; the exact numbers matter far less than that ratio.
If you have chest pain that spreads to your arm or jaw, or you have never felt this before, get it checked — call 999 in an emergency. If panic is a regular part of your life, please tell your GP: it is very treatable, and in the UK the NHS Talking Therapies service is free and self-referral.