/dictionary_and_thesaurus

Merriam Webster thesaurus and dictionary.
OneLook Dictionary and Thesaurus
Vocabulary
Words-to-Use contextual synonyms.
The Free Dictionary
Tip of My Tongue find the word you can't remember.
Rhymezone

/descriptions_and_experiences

Erowid trip reports
Drug Times drug info
Havocscope drug/blackmarket info and prices. IT FINALLY WORKS AGAIN!!!! (if it doesn't work, just try the wayback machine :3)
Diversity Style Guide
One Stop for Writers dictionary for emotions, themes, and so much more
Scarleteen sex education
Writing Realistic Injuries
Writing upper arm prosthetics good read through if you want to write a character with upper arm prosthetics
Writing With Color
EADeverell creative writing blog
Challenging Fatphobic Language in Writing: Some Alternative Vocabularies
Springhole.net writing tips, roleplaying advice, random idea generators, etc etc
The Sifter food throughout the history of the world
Yardsticks book in the open library. about kids, so if you're writing a kid it might help
Resources for describing physical things

/learning

A Poetry Handbook by Mary Oliver (on Archive)
Modern Poetry open Yale course

/legible

Readable rates readability.
Hemingway Editor is another readability rater.

/assistance

LanguageTool this is like grammarly but free (no stupid account required)
PaperRater proof reader, grammar check, and plagiarism detection

/places_to_write

StimuWrite 2 writing app for neurodivergent people
The Official Written? Kitten! shows you a picture of a kitten when you hit your target words. if you add ?search=dinosaur to the URL, it shows dinosaurs instead. you can mess around with that to show different pictures.

/generators

DND Character Generator
Fantasy name generators NOT JUST FANTASY. TONS OF STUFF.