GED

Free practice tests: math, English, science, and social studies. Review, study guide, and flashcards also offered. No account required.
https://www.mometrix.com/academy/ged-test/

Free practice tests:  ¼ length of actual test. English, math, reasoning through language arts, science, and social studies. No account required.
http://www.gedtestingservice.com/educators/freepracticetest

Free practice tests: Math, reasoning through language arts, science, and social studies. No account required.
https://www.4tests.com/ged

Free practice tests: Math, reasoning through language arts, science, and social studies. No account required.
http://www.gedpracticequestions.com/

Free practice tests: Math, reasoning through language arts, writing, science, and social studies. No account required.
https://www.test-guide.com/free-ged-practice-tests.html

Free practice tests: Math, language arts, science, and social studies. No account required.
http://www.testpreptoolkit.com/free-ged-practice-tests/

Free practice tests: Math, reasoning through language arts, science, and social studies. No account required. Practice tests, study guides, flash cards.
https://uniontestprep.com/ged-test
 
ACT

Offers free study guide and preparation booklet. No account needed for free materials:
http://www.act.org/content/act/en/products-and-services/the-act/test-preparation.html

Offers free practice test and problem-solving videos. No account needed:
http://www.mhpracticeplus.com/act.php

Offers free sample test questions. No account needed:
https://www.test-guide.com/free-act-practice-tests.html

Free online demo and test. It is free with enrollment:
https://www.princetonreview.com/college/free-act-practice-test? source=LS&siteid =je6NUbpObpQ-j6z1_254VOABGM76 C5 qhlg# !practice 

Offers sample tests in each subject No account needed:
https://www.4tests.com/act#StartExam

Offers free practice test and score review. Must have an account:
https://www.kaptest.com/college-prep/free-resources/free-events?Site Id=TnL5HPStwNw-jgv%2AZh3sIUw3W0Puyeo%20RAQ&cmp=%20aff :linkshare_TnL5HPStwNw    

GRE

Free full-length practice test from The Princeton Review:
https://www.princetonreview.com/grad/gre-practice-test# !practice

Sample GRE questions from Kaplan (20 minute workout):
https://www.kaptest.com/gre/gre-practice/free-gre-practice-questions-workout

Free full-length practice tests from ETS (downloads  available  for  PC and Mac):
http://www.ets.org/gre/revised_general/prepare/powerprep/

Overviews of the  different  test  sections  are   available  in  different formats (like large print) here:
http://www.ets.org/gre/revised_general/prepare/disabilities
 

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