Does multistreaming use more of my bandwidth?

No. However many destinations you turn on, your computer only uploads your stream once.

When you go live from Web Studio or an encoder like OBS, ApexStream receives that single upload and sends it out to YouTube, Facebook, Twitch, or wherever else you're connected — that copying happens on our servers, not yours. Your upload bandwidth requirement is the same whether you're sending to one destination or your plan's full limit.

This is different from running separate streaming software for each platform yourself, where every destination would need its own full upload from your computer.

Good to know: Your upload speed is still the bottleneck for stream quality. Keep your total streaming bitrate at or below about 75% of your tested upload speed so you have headroom for dips — that guidance doesn't change based on how many destinations you're sending to.