Do I need to download anything from AniList?

No. The list is read from AniList by your user name. A list can only be read when it is public; private entries are left out.

Why are several seasons one series here?

AniList keeps each season as an entry of its own. Let's Mark, like TheTVDB, keeps one series with seasons, so the seasons you watched become those seasons' episodes on that one series.

Why was an anime not found?

The community list has no TheTVDB or IMDb id for it yet, which usually means it is very new or very obscure. The list is refreshed every week, so a later run may find it; you can also add it by hand from search.

Will it change titles already on my list?

It only adds. Episodes you ticked stay ticked, a title you dropped stays dropped and a rating you gave is kept; it fills in the episodes and ratings that are missing.

Import from AniList

Import your AniList anime list

Type your AniList user name and your anime list comes across: each season you watched ticks its episodes on the series it belongs to, films come in as films, and your scores come with them.

Before you start

Find your AniList user name. It is the last part of your profile address: anilist.co/user/ followed by the name.
Check that your anime list is public. Entries you marked private cannot be read without signing in to AniList, so they are left out.
Sign in here, type the name below (pasting the profile address works too) and press Start import.
Wait for the report: what was added, what was updated and what our catalogue could not find. Running it again later adds only what is new.

Upload it

Create a free account or sign in, then come back here: the upload box appears on this page. Nothing leaves your browser until you press Start import.

Create a Free Account Sign In

What comes across

Yes
Watched titles
Every anime on your list that our catalogue knows: series, films, OVAs and ONAs.
Yes
Episode progress
Your progress in each season becomes those episodes ticked on the series, season by season; a finished season counts every episode it has.
Partly
Watch dates
A season or film you finished gets the date you finished it, on every episode in it. Episodes of something you are still watching get no date.
Yes
Ratings
Your score becomes 1-5 stars; a series with several rated seasons gets their average. A rating you already have here is never replaced.
Yes
Watchlist
Planning becomes plan to watch. Dropped comes in as dropped unless the series was finished anyway; paused counts as watching.
No
Custom lists
Custom lists are not kept; the titles on them come across with their status.
No
Comments and reviews
Notes and reviews stay on AniList.

How titles are matched

Every AniList entry carries AniList's own id, and a community list that links AniList, MyAnimeList, TheTVDB and IMDb ids says which series and season, or which film, it is. Nothing is matched by name. Specials and recaps that TheTVDB keeps apart from the seasons are left out and counted; an entry the list has no id for is listed after the import.

Safe to run, safe to repeat

Only the user name you type is sent to AniList, to read the public list; nothing is written there. An import never overwrites: what is already on your list keeps its progress, dates and ratings, so running it twice changes nothing. It is free.

Questions

Do I need to download anything from AniList?: No. The list is read from AniList by your user name. A list can only be read when it is public; private entries are left out.
Why are several seasons one series here?: AniList keeps each season as an entry of its own. Let's Mark, like TheTVDB, keeps one series with seasons, so the seasons you watched become those seasons' episodes on that one series.
Why was an anime not found?: The community list has no TheTVDB or IMDb id for it yet, which usually means it is very new or very obscure. The list is refreshed every week, so a later run may find it; you can also add it by hand from search.
Will it change titles already on my list?: It only adds. Episodes you ticked stay ticked, a title you dropped stays dropped and a rating you gave is kept; it fills in the episodes and ratings that are missing.