I was wondering if anyone knows of any conlang creation websites that are free to use.
I know this sounds silly but I have little experience to go on as for creating a custom language.
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There are some syntax "toys" online, eg http://www.zompist.com/gtg.html. This will help you write a (formal) grammar of your language, but you will need a good understanding of Generative Linguistics to use that.
Otherwise, what else do you need instead of pen and paper? Maybe a spreadsheet to enter vocabulary? There are so many choices to be made on so many levels that it is not really possible to automate much of it. It's not as if you would enter a few characteristics into a form, press a button, and out comes a conlang :)
There is the Vulgar fantasy language generator, which allows a small language to be generated for free, but requires a subscription for more substantial languages or advanced controls.
We all had little experience to go on when we first started making languages!
I'd actually recommend that you NOT make use of a conlang recipe resource. What you end up doing is little more than making an invented language like how the recipe writer makes an invented language.
This just defeats the purpose of the art of glossopoesy.
Instead, I'd suggest you take what experience you've got, little as it may be, and just do the hard work of language invention. Sit down with pencil and paper and doodle words and phrases thereon. Come up with some basic rules (for word order, for syllable structure, for grammar). Get yourself hooked up with a good language invention community (Conlang-L for example) and begin the learning process.
I know you are probably not still wondering, but I use https://conworkshop.com, if that helps.