Think Central from Houghton Mifflin:

https://www-k6.thinkcentral.com/content/hsp/math/hspmath/na/common/itools_int_9780547584997_/main.html

Math Learning Center:

Fractions: https://apps.mathlearningcenter.org/fractions/

Geoboard: https://apps.mathlearningcenter.org/geoboard/

Math Vocab Cards: https://apps.mathlearningcenter.org/math-vocabulary-cards/

Money: https://apps.mathlearningcenter.org/money-pieces/

Number Frames: https://apps.mathlearningcenter.org/number-frames/

Number Line: https://apps.mathlearningcenter.org/number-line/

Number Pieces: https://apps.mathlearningcenter.org/number-pieces/

Number Rack: https://www.mathlearningcenter.org/resources/apps/number-rack

Pattern Shapes: https://apps.mathlearningcenter.org/pattern-shapes/

Glencoe: choose the grade you are looking for

http://www.glencoe.com/sites/common_assets/mathematics/ebook_assets/vmf/VMF-Interface.html use arrow under manipulatives – there are lots to choose from (alphabetical order)

Interactive 100’s Chart – Splat Square http://www.primarygames.co.uk/pg2/splat/splatsq100.html

EduPlace Number Line   very flexible – good for K and 1 especially

http://www.eduplace.com/cgi-bin/schtemplate.cgi?template=/kids/mw/manip/mn_popup.thtml&filename=nmbl_prim&title=Number%20Line&grade=K