dataseek/ptbr-blogs

PT-BR Blogs (long-form, C4-derived)

Part of the MagTina350m pretrain corpus release by Dataseek under the Magestic.ai brand. This is one of nine silver-layer datasets that fed `dataseek/magtina350m-base`.

Summary

185 K long-form Brazilian-Portuguese blog posts (≥ 5 K words each) extracted from C4 by filtering Blogspot, WordPress, Medium and similar platform domains. Higher per-document quality than generic web; useful for stylistic diversity and long-context training.

Source and collection method

Source: AllenAI C4 PT-BR slice → blog-platform domain filter → minimum-length gate (≥ 5 000 words) → NFKD normalisation → URL dedup.

ETL script (in the MagTina1B repository): `scripts/etl/14_blogs_c4_v1.py` (public release of the ETL scripts is on the roadmap; until then the data card below documents the recipe in full).

Filters and deduplication

The following filters were applied before this dataset reached its silver (release-ready) state:

• —Blog-platform domains only (blogspot, wordpress, medium, ghost, …)
• —Word count ≥ 5 000 (long-form gate)
• —URL dedup across web corpora

Global URL-normalised deduplication was applied across all web-derived corpora (webpages, news, blogs) so the same article does not appear twice across those three datasets.

Schema

Columns dropped at export (kept private as ETL internals): quality_score

Size statistics

Used in MagTina350m pretrain: 1.540 B tokens (8.9 % of MagTina350m's 17.39 B-token pretrain budget).

How to load

from datasets import load_dataset

ds = load_dataset("dataseek/ptbr-blogs", split="train", streaming=True)
for row in ds.take(5):
    print(row["text"][:200])

Streaming is recommended for the larger configs. For the smaller datasets (ptbr-dou, ptbr-books-publicos) eager loading is fine.

Licensing

ODC-BY 1.0 (CommonCrawl-derived). Long-form blog content; individual posts remain copyright of their authors. Use for non-commercial research is the safest interpretation; commercial use requires per-author clearance.

Upstream attribution: AllenAI C4 + individual blog authors

Citation

If you use this dataset, please cite both the upstream source and MagTina350m:

@misc{magtina350m_pretrain_2026,
  title  = {MagTina350m pretrain corpus — PT-BR Blogs (long-form, C4-derived)},
  author = {Frasson, Ricardo and {Dataseek Team}},
  year   = 2026,
  publisher = {Hugging Face},
  url    = {https://huggingface.co/datasets/dataseek/ptbr-blogs}
}

Please also honour the upstream license terms — for CC-BY-derived data, attribution to the upstream creators is mandatory; for CC-BY-SA, downstream derivatives must remain CC-BY-SA-compatible.

Intended use

• —Pre-training, continued pre-training, or domain-adapting of Brazilian Portuguese language models.
• —PT-BR NLP research where statistically representative public-web / academic / legal / encyclopedic data is needed.
• —Reproducing or improving on the MagTina350m result.

Known limitations and PII statement

• —Text was NOT PII-scrubbed. URLs, emails, phone numbers and personal names that occurred in the source data may still be present. We strip zero-width characters and normalise Unicode but we do not run an NER pass.
• —Crawled data carries upstream biases of CommonCrawl, Wikipedia, news outlets and academic institutions present in the source. We have not audited these.
• —No safety filtering beyond langid and basic alpha-ratio gates. Hate-speech, spam and adult content present in the source remain unless caught incidentally.
• —Provenance preserved at row level. Every row has either a url, source or doc_id column that points back to upstream — this is intentional, so consumers can re-license, redact or filter.

Related releases

• —Model: `dataseek/magtina350m-base` (354.6 M params, pretrained on this corpus + 8 sibling datasets)
• —Instruct model: `dataseek/magtina350m-instruct`
• —Sibling datasets: see dataseek/ptbr-* for all nine corpora

License

odc-by