Large language models often underperform in many European languages due to the dominance of English and a few high-resource languages in training data. This paper presents TildeOpen LLM, a 30-billion-parameter open-weight foundational model trained for 34 European languages to promote linguistic equity and improve performance for low-resource languages. To address the data imbalance, we combine dataset upsampling with a curriculum-based training schedule that alternates between uniform and natural language distributions. The resulting model performs favorably compared to other multilingual LLMs despite being trained with significantly fewer computing resources. Evaluation across multiple multilingual benchmarks shows that TildeOpen surpasses existing open-weight models in text generation and comprehension, particularly for Baltic, Finno-Ugric, and Slavic languages. Human evaluations confirm an up to tenfold reduction in linguistic errors relative to leading baselines. The model and associated resources are fully open-weight and publicly available at huggingface.co/TildeAI/TildeOpen-30b. These outcomes demonstrate that careful data curation and balanced training strategies can substantially enhance multilingual model quality without increasing model size or training volume.
Figures & tables
Figure 1: Comparison of tokenization efficiency of various LLMs - boxplot over all focus languages of [Anonymized] on the FLORES 200 devtest dataset (except Albanian, which is not included in the dataset).
Unique
Ups.Ratio.
Total
LTG
0.01
2.34
0.03
GA
0.3
2.30
0.6
CNR
0.5
2.38
1.2
MT
0.5
2.16
1.1
IS
1.7
2.24
3.9
MK
3.6
2.33
8.4
Table 1: Dataset statistics in billions of unique number of tokens and tokens after upsampling.
Figure 2: Data distribution during different phases of training.
Lang. Fam.
EuroLLM
ALIA
Gemma 2
N-Germanic
4.0%
2.7%
4.6%
W-Germanic
6.4%
1.5%
4.6%
Romance
11.2%
2.3%
5.6%
Baltic
7.8%
7.9%
13.8%
Slavic (Lat.)
7.7%
4.8%
8.6%
Slavic (Cyr.)
5.6%
3.4%
5.5%
Table 2: Relative improvement of our model’s per-character perplexity compared to other open foundational LLMs on WMT24pp. Higher results are better. The Northern Germanic comparison excluded Icelandic (some models do not support it).
5-shot
EuroLLM
Gemma 2
ALIA
This work
MultiBLiMP
96.4%
95.7%
96.7%
99.0%
Belebele
82.5%
79.5%
76.8%
84.7%
ARCx
65.6%
72.4%
65.9%
65.3%
MMLUx
59.3%
69.3%
60.7%
59.9%
Exams
62.5%
71.2%
62.7%
66.6%
AVG Borda
0.8
2.0
1.4
1.8
Table 3: 5-shot performance and average Borda scores across benchmarks. Higher results are better.
Figure 3: Error analysis results - averaged errors per 100 words over two language editors (professional linguists and native speakers).
Model
ET
LV
EuroLLM
2445
2116
Gemma 2
2216
3957
This work
3168
2652
Table 4: Word count in Estonian (ET) and Latvian (LV) texts generated for linguistic error analysis.
WMT24++
GPT-4.1
EuroLLM
This Work
EN-XX
0.865
0.834
0.843
DE-XX
0.847
0.831
0.840
FR-XX
0.839
0.823
0.832
PL-XX
0.838
0.826
0.833
UK-XX
0.833
0.820
0.829
LT-XX
0.830
0.813
0.825
Table 5: Results of automatic translation quality evaluation as measured by COMET on the WMT24pp dataset. Results for GPT-4.1 added for reference.
Avg.
ChrF++
Edit
Lang.
Docs
tok.
Avg.
Max.
dist.
BG
31
650
21.9
35.3
0.94
BS
32
423
23.0
42.9
0.94
CNR
2
2094
17.5
22.6
0.93
CODE
31
2469
43.6
86.7
0.74
CS
31
512
20.7
54.1
0.94
Table 6: Memorization evaluation on the final training data slice. We report word-level ChrF++ (higher indicates greater similarity to the reference) and averaged edit distance (higher indicates greater divergence from the reference).
Computational Linguistics, Department of Linguistics University of Potsdam, Germany · 1German Research Center for Artificial Intelligence (DFKI), Berlin, Germany