Yes, both Filestage and Diffchecker offer a Free Trial.
Filestage is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Diffchecker is designed for Individuals, Medium Business and Small Business.
Pricing for Filestage Starts at $19/User/Month when Billed Yearly whereas for Diffchecker Starts at $49One Time Payment.
Some top alternatives to Filestage includes PageProof, GoProof, Ziflow, ProofCafe, QuickReviewer, Workgroups DaVinci Proof, WebProof, Coment, MediaMarkup and Proofing.
Some top alternatives to Diffchecker includes Draftable, DeltaDoc, DocSavy, Qualified, What The Diff, Workvivo, Version Story, CodeSee, Slick, DeftPDF, ui-diff and IFTTT.