So it is the most common question as most of you don't get tools for Youtube , Instagram even for steem but i just found out one tool that will solve all your problems and has it all.
Its free ,you just have to signup to start making free thumbnails
it has many Free templates and background that will do the Job for you and you can also upload custom images.
it doesn't even has the website watermark.
Services it offers:-
Facebook Post 1200px x 900px
Facebook Link 1200px x 628px
Twitter Post 1024px x 512px
YouTube Thumbnail 1280px x 720px
Instagram Post 1080px x 1080px
Pinterest Pin 735px x 1102px
Blogging & Infographics
Blog Featured Image 1200px x 600px
Blog Image 750px x 750px
LinkedIn Post 744px x 400px
Infographic 800px x 2000px
eBook Cover 1410px x 2250px
Headers
Facebook Cover Photo 820px x 312px
Facebook Event Cover Photo 1920px x 1080px
Twitter Header 1500px x 500px
Twitch Banner 1920px x 480px
SoundCloud Banner 2480px x 580px
YouTube Channel Art 2560px x 1440px
Google+ Cover Photo 2120px x 1192px
Email Header 600px x 200px
Social Media Ads
Facebook Ad (Link) 1200px x 628px
Facebook Ad (Carousel) 600px x 600px
Twitter Lead Generation Card 1600px x 400px
Twitter Website Card 1600px x 640px
LinkedIn Sponsored Ad 1200px x 627px
Display Ads
Medium Rectangle 300px x 250px
Rectangle 180px x 150px
Leaderboard 728px x 90px
Wide Skyscraper 160px x 600px
Filmstrip 300px x 600px
Pushdown 970px x 90px
Billboard 970px x 250px
Here are the images
Its not a paid review i personally liked the tool and it was easy to use
Let me know in the comments what tool do you use for making thumbnails??
Thanks :)