Other
MasterlingoBrowser extension to lookup & save vocabulary
Once installed in your browser, this will let you lookup any Persian word on any website, and allow you to add it to your vocabulary deck. You can then study that vocabulary using a spaced-repetition UI on their website.
It is laser-focused on that task, with no unnecessary fluff. The Persian word lookup is pretty decent. It won't show you any results for certain inflected grammar forms, though most words have a result.
TaranevisTransliterate between Farsi and Finglish
This is the only tool I have found which can take text written in the Persian alphabet as input, and generate the Roman transliteration (i.e. Finglish) from that. This is actually a huge challenge, because the Persian script will lack the vowel information that you'd want in the Roman transliteration. In addition, some letters will call for a different roman character based on their context. This is why sometimes you'll see stuff such as "dw bit zaba" instead of the correct "do beyt-e zibā" - this is what happens if you just map every character in the Persian alphabet to a Roman equivalent.
Taranevis is smart enough to give you the actual Finglish, as much as that is possible (I assume in some cases it will have no choice but to guess). It also uses the alefbaye2om romanization scheme, which is an interesting choice (read more about approaches to romanization in Persian if you are interested).
Contemporary IranCombines short lessons with real cultural insight.
The set of lessons on this blog don't follow any structure. Rather, they resolve around idiomatic expressions, or a subject relating to Iranian culture. The group behind it is a fantastic bunch who clearly care about sharing their love for the language.
Ali Jahanshiri's Personal WebsiteVerb conjugator and concise, but extensive grammar resource.
A real gem. In addition to many other things, this contains one of the most concise, well-organized guides to Persian grammar you'll find, and a verb conjugator that works with both Persian script as well as roman transcription.
It was a great help to me when I was coding the grammar-parser of Farsi.school, and also my inspiration to start the page you are reading right now.
Ali is taking Bitcoin-donations, and if you find is site useful, I encourage you to support him.
Cooljugator PersianConjugation Tables for Persian Verbs
This will give you the conjugation table for a Persian verb. Conveniently, it lets you input a word in any form, including in a transliterated shape. Pretty neat: You can also have it display the English translation for every individual form.
My Persian CornerBlog on Persian Food and Culture
Strictly speaking, this is not specifically for language learners (though there is a decent amount of such content there as well, including idioms and Persian music with translations). But beyond that, it deserves a mention simply because of the great insights into Iran and it's society and culture; I like to read it when I have some down time, and before I know it, I have this urge to work even harder to learn the language.
DropsTinder for Words?
Drops has a set of vocabulary and expressions categorized into thematic groups, matches each with a symbol that represents the meaning, and to test you, asks you to drag & drop the word onto the right symbol. It features pronunciations and for Persian, flawless transliterations.
There is no grammar instruction, and you don't really deal with whole sentences, so I don't think you can learn the language with it, but it might be a nice way for beginners to study vocabulary.