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duo/eu dev blog

The FAQ page became a little bit longer than intended, so I thought I'd better post a more detailed description of some existing and upcoming features here. There will be some retrospective records first and then I'll countinue from where we are at the moment. Stay tuned! :)


What's new

21.02.2022 · Cached data (yet again)

It keeps happening every now and then: I get a "too many requests" error from duolingo servers so I have to force the cached mode until everything gets back to normal. It can be a few minutes or a few hours but it's getting more and more obvious that with ever increasing number of usernames I will have to re-think the update strategy to exclude SEO bots (I never tried to please them anyway) and update only those usernames for those users who do use duome "actively" for their studies. There may be a one-time request, maybe a button that you will have to click once to confirm that you need your username to be updated on a regular basis.

31.08.2021 · Cached Tips

There are some trees that used to have the old-style tips and notes which disappeared later on for some reason — Duome will now display the latest non-empty set of tips for these trees, English from French course being an example.

18.08.2021 · Predictions

I made a few changes to how the tree completion date is being predicted and now there's a comment asking you to please, keep in mind that 8.08% of your lessons were... — note the percentage. Stories and some other challenges fall into this category and they are being excluded from the calculation. Everything that is actually bound to a specific skill id - counts.

08-13.08.2021 · Cached data...

There's an ongoing issue with Duolingo API usage limits probably due to some updates/maintenance inside Duolingo, I'm waiting for a solution from Duolingo Team; for the time being Duome mostly displays your recently cached data. I have some ideas about how it could all be optimized *big time*, but there's not too much that can be done without Duolingo Dev Team support, so let's keep our fingers crossed and hope for a solution sooner than later. I'll give you more details as soon as I get the answers..

August 14 update: it seems to be ok now, but I'll need to watch it more closely and do some testing to be on the safe side. There may still be some limitations for a little while.

09.07.2019 · Tips & Notes, illustrated

Consider these "beta" for it's not too easy to maintain the original formatting so I had to discard some (probably) less important "visual representation features" like colored or bold text, but all these new tips and notes should be properly illustrated and all the voice clips are still there.

Sometimes there are up to 9 (or it may well be an infinite number of) versions of tips and notes for some specific lessons so I'm still not sure about the proper way to store them and/or decide which one is the most correct and up-to-date — sometimes there can be a typo fixed and sometimes there are a few more paragraphs of text and a few more pictures, you can see some examples in Spanish tips — there are male, female, "updated text", and "more pictures" versions of some tips and notes.

Sorted in alphabetical order.

By the way: if there are more tips and notes like these and I'm still unaware, be sure to tell me!

30.05.2019 · Sort by Crowns/Lessons

There's now subordering by lessons completed within a crown level when you order your skills by crowns; there's also a Sort by Lessons option which works in a slightly different manner - I'm not sure if this one is really necessary but you can try it out as long as it's still there.

Some of you were missing this little piece of information, so the XP points needed for the next level are now visible on the mobile version of duome.

19.05.2019 · Data Integrity Checks

A quick note: Duome does check streak length vs account creation date (and a few more things to ensure data integrity), so if there's something totally unrealistic, it would be excluded from the rankings.

Another quick note: I'm still fine-tuning it a little bit and since there may be different reasons there will also be explanations to why a certain username is excluded (a fine text next to a username saying streak / reg date mismatch or something like that); if there's no explanation then it's probably nothing "terribly wrong", but you may need to refresh your duome page if you cannot see your username where it should be; most of the time the gray color means "a username failing to auto-update more than once for whatever reason" and these need to wait longer for another chance. A manual update would do the job just fine.

Update: so, there are currently 5 possible reasons for a username to be "grayed out":

Dear duonks, there's nothing wrong with your profile, it must have been caught out by an "accident" during this fine-tuning process I mentioned earlier — I'm sorry about that and surely it was something unintended:) You're still #3/#5 (effectively) on the Golden Owls / Crowns HOF, and it's simply amazing!

14.05.2019 · Crowns

1) Duome now displays crowns for everyone regardless of their streaks and 2) crowns should now be in-sync with the totals displayed on (previously Duome used to calculate crowns per skill/level using extended profile data which isn't always in-sync with what duolingo thinks about our skills — remember those wicked missing lessons?..)

Please, allow a few days to have duome auto-update Crowns HOF data or refresh your duome page to force the immediate update if you can't wait to go up in the standings =)

06.05.2019 · Cached Trees

Ok, this was originally requested by Thomas.Heiss and it's my pleasure to say that there is now a possibility to view our "cached" trees progress. I allowed Duome a few weeks to collect some data so it's old news already, but anyway, I hope you enjoy it :)

A few notes on this feature:

26.04.2019 · Live Data Issue · Fixed

There seems to be some issue with duome being unable to fetch extended profile data this morning so your personal duome pages do not work at the moment because they were designed to show live data - I'm talking to duolingo tech support to understand the issue while I'm tuning the code a little bit to display cached data should there be a similar issue anytime in the future. Hold on.

Update: Thank you Vivian for some magic:), it would have been much harder to make it without your assistance, but you were there for all of us when it really mattered :)

23.03.2019 · Happy Birthday Duome

It has been two years and maybe slightly more - was registered on March 23, 2018 while the original was registered on March 11, 2017 and I think I already had this idea on my mind for quite a while before that day. I didn't plan on sharing it with anyone too early before everything is polished until one day I suddenly realised that more and more people are already talking about it in more and more languages including Japanese! I never had a chance to reach out to and do something for so many people around the world and it leterally means the world to me.

Thank you for loving duome )

20.02.2019 · Updated French T&N's

Enjoy French Volunteer Contributor Tree Tips&Notes, all in one place, printable, as usual. These cannot be auto-updated yet even though there's definitely a possibility. It could be somewhat easier if there were a changelog on the source page to help track future updates in one place instead of 77 individual pages. Anyway, we can still have "less frequent" updates — they can be atomated and triggered once a month, for instance.

08.02.2019 · Verbs: ...

Just a quick (re)naming template for Thomas.Heiss to bring at least some of those "verbs" skills back in place when we sort our skills by name.

25.01.2019 · Performance issues

You may have noticed the 327 minutes downtime earlier this day. Basically, it's always about what I can do or what I wish I could do vs what my web host can handle vs how much I need to optimize everything to make it possible and keep my hosting provider happy — they are taking it easy, but Duome is hitting the limits all the time so they keep suggesting that I probably need a more powerful hosting plan for this project or I need to optimize something within a certain time limit - Duome userbase has grown up from under a thousand to more than 22 thousand records at the moment and I had to learn quite a few tricks along the way, which is kind of fun on its own.

This one below is the server load chart throughout January 2019:

September 2018, somewhere in the middle of the words tab development:

I was actually unaware about the November downtime, there was probably some maintenance scheduled by my web host so this can also be the reason. Anyway. It happened before and it may happen again, but there's always a solution and I can only say that Duome will be here to stay for as long as you need it.

You don't need to be worried about this.

25.10.2018 · Words!

You may have noticed that there are now an awful LOT more words on the words tabs on our progress pages: a huge thank you to Olja. for helping me collecting these words for virtually every existing language course :), I'll give you some more details later on, but there's another good reason for this post: she has a beautiful streak of 1111 days today and I know she has been an inspiration for many, myself included... )

25.10.2018 · Billionaire Hall of Fame anyone?

Wonders of Duolingo: one BILLION lingots for AJ.Noh, period :)

22.10.2018 · Features

In response to Thomas.Heiss ideas: es war ein wirklich langer Post aber ich habe es gelesen und werde darüber nachdenken :)

Yes, there are some ongoing issues with "big data" and I need to balance server load all the time and it's exactly the reason why I choose not to cache more data for now — it will put a lot more stress on the database which is already beyond all limits, so I keep learning the new ways to optimize everything. It's not as fun as some other anticipated and upcoming features but... it's interesting. But every time I introduce something new, I have to wait and see how does it affect server load and then reiterate and rewrite some parts of the code, wait and see if it helps, etc. And I need to pace the changes to know what makes a difference if there's a big difference and I need to do something about it.

16.10.2018 · Fixes

There are some known issues described in FAQ, one of them concerning the word counts being occasionally corrupted on duolingo side, for this reason you may see somewhat surprising progress data for some of your inactive languages (a golden owl @ 100xp / level 2 for a language pair that you barely started and never really learned) and in language tables like this — those 1808 vocab entries seem to be wrong. I implemented a workaround preventing this corruption, but there are some already corrupted trees and they would have to be fixed eventually — as soon as duome sees them. If you do have some of those low-level-golden owls or your word count is reset to zero, you may wish to update your owl: switch to this language pair, do at least one lesson, refresh your duome page. Your data is now fixed and protected from future corruption.

This may happen to some of the languages for your current base language except the currently selected pair. It happened to my es»it and it»fr trees, it used to happen to my Catalan tree particularly often and I've seen someone in the forums reporting their word counts suddenly disappear as well — seems to be exactly what happens to my Catalan.

More insight: more or less every list would contain some records with empty vocabulary column with or without crowns at the very bottom of the list; if there are crowns but no vocabulary, the word count data is lost by duolingo and needs to be updated; if there are no crowns, the user didn't revisit his/her tree since the crowns update, i.e. there must be a very sad and neglected owl on the top of that tree... =|

Equally, there would be some low-level/high-vocab records at the top of the list, usually it's more vocabulary than possible for this language pair — somehow these numbers come from a different base language (e.g. es»it tree, but en»it data). These are obviously wrong.

06.10.2018 · Hawaiian/Navajo

These numbers on the duolingo courses page don't seem to be updated realtime, but anyway, there are supposedly 211+85 active learners of Hawaiian and Navajo at the moment while there are 38+30 52+37 students listed for these languages on duome (62+33 84+75 with level 1 students included). It might be interesting to keep track of these numbers for a little while to see how they correlate. The next youngest course is Indonesian with 40k+ 43K+ learners at the moment but only 423(623) stundents listed on duome. Catalan ratio is 704K vs 729(831).

08.10.2018: 2.42K/1.95K » 156/139 = 6/7% ... the ratio is falling down fairly quickly from somewhere around 30% in the very beginning to 1% (Indonesian) and further down to 0.1% (Catalan) while the courses are being adopted by more and more students.

05.10.2018 · More Words

Playing with a relatively new Words tab on our progress pages. The words list may still be empty or incomplete for some languages while some others are ok and some have tags assigned to each word - if you see them, you can filter the list by clicking any of the gray labels at the top of the list, or you can reset the filter by clicking × ... or you can use the search field where you can use both the original language with all its special symbols, accents, etc., or you can use transliteration if you don't have the proper keyboard layout installed on your PC. If you search for "nouns" it will list all nouns (and pronouns - it's a full text search, so everything that matches your input will be displayed). Finally, there's a small blue icon next to each word - it should take you to a corresponding skill practice session on and maybe duo will throw in some sentences containing this word if you are lucky.

04.10.2018 · XP Raw Data

If you click the raw button next to the daily chart title, you can now see the raw XP data [datetime/improvement] converted into readable date/time for your local timezone. This would hopefully make troubleshooting a little bit easier.

11.09.2018 · Days To Go

A tick on someone's wishlist way before Christmas: you can now see how many days you would have to study at your current pace to finally get a golden owl for your current tree (see exclamation mark next to the lessons value on your progress page).

Update: the calculation is based on recently completed lessons excluding "less successful" or abandoned timed practice sessions ending with less than 10 points — these lessons don't take you closer to your golden owl anyway...
Read more

06.09.2018 · Words

There would now be a lot more words (hopefully every single word available) listed under the lightbulbs on your progress pages for some courses, starting with Catalan, Spanish, French, German, Italian and Portuguese for now. The words that weren't previously included are shown in bold.

Update: Danish, Swedish, Polish and Ukrainian are now also available.

05.09.2018 · Please, welcome (and more)

05.09.2018 · Your languages in red and black

Since I don't really remember how long, you don't have to show all your owls to duome to have them counted. Instead, duome tries to figure out how complete all of your trees are in one step based on your current vocabulary so you could see all of your languages instantly — you would find them on the list on your progress page along with with levels and word counts painted either black or red. So, red means a completed tree — a wild guess based on your vocabulary. It may not be 100% accurate as it can still overlook some of your owls for some reason (a new language course or a new tree version with extended vocabulary, for instance), but it rather works than it doesn't, and if your existing owl is missing, simply show it to duome as usual. This red coloring was actually a test feature, but it's still there in case of any future updates to existing language courses to help identify that there's something happening in the background (e.g. an A/B test of a new tree version, maybe).

09.07.2018 · Original Sort Order

I don't read along the forums for quite a while already, but whenever I can, I'm trying to fulfill at least some of your wishes: the progress page skills can now be sorted by their original sort order. Enjoy :)

09.07.2018 · The Small Red Dot Demystified

The small red dot on the progress page simply replaces the "+x lessons missing" line for L5 skills to make it slightly less annoying/confusing. Taking any skill to level 5 is quite an achievement in itself and I didn't want to take anything away from it, and those missing lessons can be way too frustrating at L5. Anyway, a small red dot would be there if there are some "missing_lessons" in this particular skill in your extended profile. Just a small reminder that you may still wish to take care of those missing lessons as soon as there's a chance to take care of them.

29.06.2018 · Golden Owls (in)cosistency

Duome used to count individual lessons to figure out how complete is your tree and do you really have a golden owl, this is why it didn't show some of your escaped golden owls in the past few weeks, but it's also true that Duome should reflect the achievements awarded by Duolingo and not define its own, and since Duolingo itself seems to be treating our owls in a different manner after the Crowns update, the criteria is now changed to reflect Duolingo's new logic, so if you do have a golden owl and it's visible on, it should also be visible on Duome from now on.
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27.06.2018 · Testing out of crown levels

Not sure if this is a new feature for everyone or is it a yet another A/B test but it looks like we can now test out of the crown levels (yay!), so there are now the "test out" links on our progress pages as well.

By the way, it's exactly 10K users on duome today.

31.05.2018 · Streak Freeze Hall of Fame

The streak freeze page is rearranged a little bit to make it look more like a hall of fame: there are only 11 people who never used a streak freeze since 2013, half a hundred more who keep it up since 2014 and quite a few almost a hundred duolinguists having 1000+ days streaks while not having a streak freeze equipped. Scary.


From this day on is supposed to be redirected to so let's keep it up from here with the new domain: seems to have been chosen by 67.3% of 1000+ voters (as of 31.05.2018) and there's a tie between the other two options, each having around 16.3% of the votes.


The default sort order for skills on the progress page is now: higher strength · more crowns · first learned · unlocked

This puts golden skills first (regardless of how many crowns you earned for these skills), while the rest of the list would be sorted more or less by crowns (and the colors associated with them), the entire page looks a little bit nicer this way.

16.04.2018 · The future of

Durung the past few weeks I have been talking to Severin Hacker, the co-founder and CTO of Duolingo. To make a long story short: they do like the idea, but they need to own the domain and they're going to redirect it to so the old forum links will stop working in a couple of weeks from now.
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