v1.0.0b1

[BETA] This is a beta release, and I would love to get feedback on this direction!

It's finally here! This is the first beta of BERTopic 1.0 (there will definitely be more).

My idea was to rewrite a lot of what was under the hood while its API stays as it was wherever possible. This would make it easier for future development and increase stability of the underlying code.

As with any pre-release, you can only install it when explicitly running:

pip install bertopic==1.0.0b1

Nothing changes for those that are using BERTopic in production or in their pipelines, you will still install 0.17.4 unless you specifically run the above command.

If anything breaks (and I have no doubt it will with this first beta), please let me know in the issues.

Some code will need a small update, which the migration guide shows for every change.

EmbeddingGemma 2, the new default embedding model, embeds text, code, images, video and audio in one space.

Highlights:

• Multimodal topic modeling with text, images, audio, video and code
  • Pass them to .fit_transform with images=, audio=, video= and code=, with or without documents
  • MultiModalRepresentation describes images and frames of videos with a vision model and transcribes audio with a speech model, such as Whisper, so topics of media get keywords too
  • See each topic's collage, frame sheet and audio montage with .visualize_media()
• EmbeddingGemma 2 is the new default embedding model
  • BERTopic() uses its text model for every language, and BERTopic(embedding_model="google/embeddinggemma-2") also embeds images, audio and video in the same space
  • BERTopic embeds the first 1,024 tokens of each document, since the model sets no length limit of its own
• LLM representations were rewritten around one request loop, with Ollama as a new representation model, structured output and current default models
• Get polars instead of pandas dataframes with bertopic.set_output("polars")
• Added support for Python 3.14
• 80 issues fixed, all listed below

Multimodal:

• .fit, .fit_transform, .transform, .update_topics, .merge_topics, .reduce_topics and .reduce_outliers take images=, audio=, video= and code=
  • With as many documents as items, each document describes the item at its position, as a caption does
  • With any other number, the documents are rows of their own, so you can model unrelated documents and media together
  • Media can be passed as file paths, which is advised, or in memory
• MultiModalBackend takes one model for every kind, or a model for each kind with image_model=, audio_model=, video_model= and code_model=
  • .embed_media(items, modality) embeds items of one kind, such as .embed_media(images, "image")
  • Media is embedded a few items at a time (16 images, 4 recordings or 1 video), since one video can be thousands of tokens
• MultiModalRepresentation replaces VisualRepresentation
  • It describes up to nine items of each kind per topic, with a model for each kind (image_model=, audio_model= and video_model=), and the descriptions become the topic's keywords
  • A model can be a name, a transformers pipeline or any callable, such as a call to an API
  • Items that already have text, such as captioned images, keep it
  • Video is described through three frames of each clip, taken from the middle of equal stretches of the clip, which you can change with nr_frames=
• Every topic gets one summary per kind of media: a collage of its images, a frame sheet of its videos and a montage of the first two seconds of its recordings
  • representative_items_ holds every topic's representative media, and representative_images_ its collage
  • .get_topic_info() shows them in a Representative_Items column
• .visualize_media() shows each topic's collage, frame sheet and montage in a table, which a notebook shows inline
• .visualize_document_datamap() takes the same media as .fit, and shows an image, or a video's middle frame, when you hover over its point
• Saving with safetensors or pytorch keeps every summary, and the representative items as their paths
• Two new extras: pip install bertopic[audio] and pip install bertopic[video]

Embeddings:

• EmbeddingGemma 2 (google/embeddinggemma-2) is the default embedding model for every language
  • BERTopic() loads only its text model, and passing its name loads the full model, which also embeds images, audio and video
  • Documents get its Clustering prompt, and short texts that BERTopic compares with documents, such as search terms, zero-shot labels, seed words and keywords, are embedded without it
  • Without a GPU that runs bfloat16 natively, as on most CPUs, a model loaded by name runs in float32, which is several times faster there
• A custom backend can define embed_words to embed those short texts differently from documents
• .update_topics takes embeddings= to calculate the topic embeddings from your document embeddings

Representations:

• .get_representation(topic, aspect) returns a topic's full representation, such as its Keywords, an LLM's Label, a StructuredJSON answer or its Media, while .get_topic keeps returning words and scores
• LLM representations share one request loop, so a custom LLM representation only needs to implement _generate(prompt)
  • Added Ollama as a representation model
  • Pass json_schema=True, or a schema of your own, for a structured answer, which is kept as a StructuredJSON representation
  • An answer without a label, or a prompt that OpenAI refuses for its content, gets "No label returned" and a warning, so one topic does not stop the fit
  • OpenAI and LiteLLM default to gpt-6-luna and Cohere to command-r7b-12-2024
• TextGeneration sends models with a chat template their prompt as a chat message, and uses DEFAULT_CHAT_PROMPT for them by default
• LlamaCPP("model.gguf") works again and uses the chat template in the GGUF, with a 16,384-token context

Changes in behaviour:

These change your output without raising an error:

• probabilities_ has one column per topic, including the outlier topic when there is one, and each row sums to 1. The matrix from .transform has the same columns, and .delete_topics adds the probabilities of a deleted topic to the outlier topic
• Representative documents are sampled differently than in 0.17.4, so they can differ, and a topic no longer lists the same document twice
• evolution_tuning=True, the default in .topics_over_time, now averages each timestamp with the previous one as documented, and global tuning uses each topic's own row
• .update_topics keeps your vectorizer, c-TF-IDF and representation models instead of resetting them to their defaults
• .topics_over_time, .topics_per_class and .hierarchical_topics show c-TF-IDF keywords. Pass use_representation_model=True to run your representation model on every timestamp, class or merged topic
• nr_topics and .reduce_topics never merge zero-shot topics, which keep their names, so nr_topics must be larger than the number of zero-shot topics plus the outlier topic
• MaximalMarginalRelevance without an embedding model returns its top_n_words instead of 30 words
• .find_topics no longer returns the outlier topic
• A topic that is listed twice in a plot's topics= is drawn once
• .get_document_info(docs, df=df) puts the columns of df first

API Changes:

The migration guide shows the code for each of these:

• VisualRepresentation is replaced by MultiModalRepresentation(image_model=...)
• Fitted attributes, such as topics_, topic_sizes_ and c_tf_idf_, can no longer be overwritten. Use .update_topics(docs, topics=new_topics) instead, and remove topic_model.topics_ = ... from online topic modeling, since .partial_fit now keeps track of all topics itself
• The media aspect no longer gets a column of its own in .get_topic_info(), and topic_aspects_ holds its captions
• LangChain takes a chat model instead of a chain, Cohere takes a cohere.ClientV2, LlamaCPP's pipeline_kwargs is now generator_kwargs, and OpenAI no longer accepts chat=True
• TopicMapper, topic_mapper_ and mappings_ are removed
• An embedding_model that BERTopic does not recognise, such as a lambda, raises a TypeError instead of being replaced by all-MiniLM-L6-v2
• Models that 0.17.4 or earlier saved with safetensors or pytorch load as before, but a pickled model, which .save gives by default, has to be saved again with safetensors in 0.17.4 first
• A saved pointer to a model with a Clustering prompt, such as google/embeddinggemma-300m, now embeds new documents with that prompt

Under the hood:

• Topics are no longer tracked in pandas dataframes. Topics, Topic, Corpus, TopicMapping and TopicHierarchy hold all topic and document information, and topic_model.topics gives you the Topics object
• Each row of the Corpus has a modality, which is what multimodal topic modeling builds on
• Representations are typed: Keywords, Label, StructuredJSON and Media
• Probability columns follow the topic IDs, and one mapping keeps predictions, probabilities and topics in line through merging, reducing and deleting topics
• Dataframes are created through narwhals, so BERTopic returns pandas by default and polars with bertopic.set_output("polars")
• hierarchy_ holds the last calculated hierarchy, which .get_topic_tree() uses when you pass none
• A much larger test suite, with tests on the topic data layer, rules that hold for every fitted model, the public signatures of 0.17.4, and every LLM representation without an API key
• Custom representation models implement .extract_topics(topic_model, corpus, topic_representations, c_tf_idf) and return a representation for each topic, such as Keywords or Label
• MultiModalBackend.embed_images is replaced by .embed_media(images, "image"), and .embed no longer takes images
• TextGeneration takes text-generation pipelines only, since transformers 5 removed text2text-generation, and a prompt with a chat template written in by hand gets it twice
• WordDocEmbedder and BaseEmbedder's word_embedding_model are removed
• CI runs on Python 3.11 to 3.14

Dependencies:

• Python 3.11 or newer, so Python 3.10 is no longer supported
• sentence-transformers>=6.1 and transformers[vision]>=5.19, which installs Pillow and torchvision since EmbeddingGemma 2 needs them even for text
• narwhals>=2.0
• polars is optional, for bertopic.set_output("polars")
• New extras: audio (librosa and soundfile) and video (torchcodec)

Fixes:

• Probabilities and .transform
  • probabilities_ has a column for every topic, including the outlier topic, so each row sums to 1 and every column lines up with its topic (#905, #1508, #1807, #2017)
  • Probabilities follow the custom topics passed to .update_topics (#1387)
  • .visualize_distribution shows the outlier topic (#1424)
  • Documents are optional in .transform, so you can predict from embeddings alone (#366)
  • .transform takes a single document with a 1-D embedding (#2018)
• Outlier reduction and .update_topics
  • .update_topics keeps your vectorizer, c-TF-IDF and representation models, so stop words and n-grams survive outlier reduction (#1638, #2114, #2148)
  • Topic embeddings follow the documents in .update_topics, also after saving and loading, and embeddings= gives the exact centroids (#1861, #2198, #2316)
  • .reduce_outliers on a merged or loaded model raises a clear error that points to .update_topics(docs) (#1944)
• Topic reduction, merging and deleting
  • nr_topics="auto" works when every document is an outlier (#1559, #1893, #1925)
  • .merge_models keeps custom labels and representative documents (#1692, #2222)
  • .delete_topics works after .set_topic_labels, and .topics_over_time after .delete_topics (#2529, #2530)
  • .hierarchical_topics and .topics_over_time on a merged model raise a clear error that points to .update_topics(docs) (#1682, #1700, #2152, #2343)
  • Documented that saved models do not keep their representation models, so set topic_model.representation_model after loading to update aspects with .reduce_topics (#2035)
• Zero-shot and guided topic modeling
  • Topic reduction no longer merges zero-shot topics away (#2409)
  • Topic names and sizes are right when every document matches a zero-shot topic (#2384, #2447)
  • Guided topic modeling no longer changes the embeddings you pass to it (#2277)
• Hierarchical topics and topics over time
  • Distances within floating-point noise of zero no longer crash .hierarchical_topics (#1418, #1573)
  • The progress bar of .hierarchical_topics follows verbose (#1908)
  • .hierarchical_topics(use_representation_model=True) names the merged topics with your representation model (#2503)
  • Evolution tuning in .topics_over_time takes effect (#2370)
• Online topic modeling
  • topics_ covers every document after .partial_fit (#1427, #1626)
  • The documented online example runs on scikit-learn 1.8 (#2097)
  • Models with an OnlineCountVectorizer can be saved with safetensors and pytorch (#1431, #2196)
• Saving and loading
  • Representative documents are saved and loaded (#1811, #1975)
  • Saving no longer fails after .partial_fit (#2432)
  • pytorch models are loaded with weights_only=True (#2264)
  • BERTopic.load(path, embedding_model=...) no longer loads the saved embedding model first (#2493)
• Representations
  • A topic no longer lists the same representative document twice (#1736, #2495)
  • MaximalMarginalRelevance works with fewer words than top_n_words (#2266), and keeps top_n_words without an embedding model (#2323)
  • A list of representation models works as the main representation (#1846)
• LLM representations
  • Added Ollama (#1824) and moved LangChain to chat models (#2187)
  • OpenAI no longer forces stop="\n", which GPT-5 rejects and which cut thinking models short (#2423, #2469, #2481)
  • A prompt that OpenAI refuses for its content, or an empty answer, gets "No label returned" instead of stopping the fit (#2342, #1979, #2353)
  • Every LLM representation is tested without an API key (#2051)
• Embeddings and installation
  • import bertopic no longer fails when an optional package, such as openai or langchain, cannot be imported (#1655, #1973)
  • The minimum version of sentence-transformers is one that BERTopic runs on (#2331)
  • An embedding_model that BERTopic does not recognise raises a TypeError instead of being replaced by MiniLM (#1952)
  • Model2Vec backends no longer share their distillation vocabulary (#2544)
  • A vocabulary of a single word works (#2034)
  • Documented that language="english" removes characters such as German umlauts, which language="multilingual" keeps (#2468)
• Visualizations and search
  • custom_labels with an aspect works in .visualize_hierarchy and .visualize_topics_over_time (#1503, #1504)
  • .visualize_topics raises a clear error with fewer than 3 topics (#1512, #2247, #2363)
  • A dataframe passed as docs raises a clear error (#1589)
  • .visualize_topics_per_class and .visualize_topics_over_time no longer change the dataframe you pass (#2154)
  • .find_topics takes a list of search terms (#2392, #2475)
• Multimodal
  • Each topic's images, with .visualize_media() and in the datamap (#2236)
  • The multimodal guide works with pandas 2 (#1884)
• Development
  • Tests for every step of the pipeline (#2206), and the duplicated code in _bertopic.py is gone (#2497)

Thank you:

A big thank you to everyone who opened an issue that is fixed in this release: @1jamesthompson1, @6801318d8d, @aerithnetzer, @Afloat16, @ajdapretnar, @akalra03, @alegallo1511, @anirban-mu, @aw578, @aymanmh, @chadlillian, @chentitus, @daianacric95, @DamienBukudjian, @dhammo2, @donottakemyusername, @ElskeNijhof, @eschaffn, @felipeinagaki, @franz101, @GiannisKav, @gnimpf, @Hanqingxu123, @henrique-back, @huisman, @inesmcm26, @IsaacGreenMachine, @jhrystrom, @jianzhang-ia, @kevinmneal-archive, @luismavs, @mad-carto, @manas007, @mepearson, @MHZach, @mjaved-nz, @mzeres, @nabsiddiqui, @nhansendev, @noelleninja, @nrydanov, @OnAnd0n, @Paignn, @peiguo9028, @pidefrem, @PipaFlores, @powerhorse1986, @raffaelemancuso, @rap8, @rcprati, @rhys-thompson-deel, @sam-baumann, @schoobani, @sdehm, @sercankiyak, @shivamtawari, @shj37, @Skar0, @SkylarOconnell, @soonernotfaster, @stevetracvc, @sutgeorge, @terilias, @TheAIMagics, @vidieo, @yml-blog, @yourlogarithm, @zilch42, @zpbrent.