I plan to use Spellingcity.com with first graders. According to the website,
We are an online spelling program that makes practicing for spelling tests fun. SpellingCity.com has:
– Over 35,000 spelling words and eight spelling games!
– A REAL person who says each word and sentence
– Thousands of free spelling lists. Or save your own
Let's Go Somewhere on 7/30 
I use SpellingCity. It’s the greatest Spelling Website ever!
It has the basic test, over 42K words, ten games, handwriting worksheets, and printable games.
I also use Spellingcity. It’s awesome. I like that I’ve found some great resources there such as some really good info on compound words, sound alike words, and dolch words.