List of places to find contract work

Small shops/boutique agencies

Forward - https://work.forward.id/
Arkency - https://arkency.com/join-our-team/

Smaller/niche/remote sites

Rails devs - A reverse job board for Ruby on Rails developers - https://railsdevs.com/
Hacker News Monthly Hiring Discussions - https://news.ycombinator.com/submitted?id=whoishiring
DEV - https://dev.to/listings/jobs
Work in Startups - https://workinstartups.com/job-board/jobs/developers/freelance/
Jobserve - https://www.jobserve.com/
Jobsite (UK specific) - https://www.jobsite.co.uk/
Refactoring Jobs - https://refactoring-jobs.pallet.xyz/jobs
Part time tech jobs - http://parttimetechjobs.co/
We Work Remotely - https://weworkremotely.com/remote-contract-jobs#job-listings
FlexJobs - https://www.flexjobs.com/
Remotive - https://remotive.io/remote-jobs/software-dev
Authentic jobs - https://authenticjobs.com/
Jobspresso - https://jobspresso.co/
Women Who Code - https://www.womenwhocode.com/jobs?time_status=contract

Language/framework/field specific

RubyNow - https://jobs.rubynow.com/
Python Jobs - https://www.python.org/jobs/
React job boards - https://www.reactjobboard.com/
JavaScript job XYZ - https://javascriptjob.xyz/Vue jobs - https://vuejobs.com/
Javascript JS remotely - https://jsremotely.com/
Blockchain job board - https://www.blockchainjobboard.org/