I know you're just asking for sites and not approaches to finding contract work, but getting in with a very promising early stage company through contract-to-hire [that allows remote] is probably the most sustainable way to go.
Doing one contract project after another at an hourly rate just doesn't scale well financially and finding a next decent client can be like pulling teeth.
Remote OK - https://remoteok.io/
Stack Overflow - https://careers.stackoverflow.com/jobs?allowsremote=True
LiquidTalent - http://www.liquidtalent.com/
Working Not Working - http://workingnotworking.com
Hired - https://hired.com/contract-jobs
Gigster - https://gigster.com/
Mirror - http://mirrorplacement.com/
Metova - http://metova.com/
Mokriya - http://mokriya.com/
HappyFunCorp - http://happyfuncorp.com
Savvy Apps - http://savvyapps.com/
Clevertech - http://www.clevertech.biz/
Workstate - http://www.workstate.com/
AngelList - https://angel.co/jobs
I know you're just asking for sites and not approaches to finding contract work, but getting in with a very promising early stage company through contract-to-hire [that allows remote] is probably the most sustainable way to go.
Doing one contract project after another at an hourly rate just doesn't scale well financially and finding a next decent client can be like pulling teeth.