Model components / Training & synthetic datasets

OpenHermes 2.5

Synthetic instruction-following dataset of roughly a million conversational examples, compiled and generated primarily from GPT-4 outputs across math, code, roleplay and general-knowledge tasks. Created by Teknium as an expansion of OpenHermes 1, it trained the OpenHermes 2.5 fine-tunes and is used as a base supervised-tuning mix by open instruction models.

The dataset card declares no license and no license file ships with the data, which the openness axis resolves. Verified 2026-08-13 via the teknium/OpenHermes-2.5 dataset card and its raw README.

Openness

3 medium confidence

3.0

license: not-clearly-stated-on-card(no license field in the card YAML, no license section in the card body, no LICENSE file in the repository and no license tag on the Hub API)
card: present
ungated: yes
format: JSON/Parquet
rows: ~1M

Publicly downloadable and ungated with a full card, but with no license anywhere the publisher controls: the card front matter carries language, pretty_name and tags and no license key, the 126-line body runs from the source list through the format description to the citation without a terms section, the repository holds only .gitattributes, README.md and openhermes2_5.json so no LICENSE file ships with the data, and the Hub API returns no license either. Files that download freely without a grant of rights are not open, and not closed either, which is what the gated class records here.

https://huggingface.co/datasets/teknium/OpenHermes-2.5 recorded 2026-08-13
Public ungated dataset card, ~1M rows, synthetic/GPT-4 tags
https://huggingface.co/datasets/teknium/OpenHermes-2.5/raw/main/README.md recorded 2026-08-13
card front matter is language, pretty_name and tags only, with no `license:` key; the 126-line body covers the dataset description, the Lilac integration, the full list of constituent source datasets, the sharegpt format and a citation, and contains no occurrence of "license" or "terms"
https://huggingface.co/api/datasets/teknium/OpenHermes-2.5 recorded 2026-08-13
cardData carries no license and the repository has no `license:` tag; siblings are .gitattributes, README.md and openhermes2_5.json, so no LICENSE file ships with the data

Adoption

3 high confidence

3.0

17,420 downloads in the trailing 30 days for teknium/OpenHermes-2.5, which bands at 10K-100K, level 3 on the dataset adoption scale.

https://huggingface.co/api/datasets/teknium/OpenHermes-2.5 recorded 2026-08-13
17,420 downloads in the trailing 30 days for teknium/OpenHermes-2.5

Capability

3 high confidence

3.0

Attributed gains inside SmolTalk (MMLU/BBH/WinoGrande) but no standalone ablation; superseded by Hermes 3 and survives as a 100k SmolTalk slice.

https://arxiv.org/html/2502.02737v1 recorded 2026-08-13
SmolLM2 paper credits a 100k OpenHermes-2.5 subset with MMLU/WinoGrande/BBH gains

Verified 2026-08-13