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Integration: Mastodon Fetcher

A custom component to fetch a mastodon usernames latest posts

Tuana Çelik

The MastodonFetcher is a simple custom component that fetches the last_k_posts of a given Mastodon username.

This component expects query to be a complete Mastodon username. For example “ tuana@sigmoid.social”. If the provided username is correct and public, MastodonFetcher will return a list of Document objects where the contents are the users latest posts.


Run pip install mastodon-fetcher-haystack to install the latest available release.


Because the component returns a list of Documents, it can be used at the same step that a Retriever would normally be used. For example, use it in a Retrieval Augmented Generative (RAG) pipeline as follows:

from haystack import Pipeline
from haystack.nodes import PromptNode, PromptTemplate, AnswerParser
from haystack.utils import print_answers
from mastodon_fetcher_haystack.mastodon_fetcher import MastodonFetcher

mastodon_fetcher = MastodonFetcher()

prompt_template = PromptTemplate(prompt="Given the follwing Mastodon posts stream, create a short summary of the topics the account posts about. Mastodon posts stream: {join(documents)};\n Answer:", 
prompt_node = PromptNode(default_prompt_template=prompt_template, model_name_or_path="text-davinci-003", api_key=YOUR_OPENAI_API_KEY)

pipe = Pipeline()
pipe.add_node(component=mastodon_fetcher, name="MastodonFetcher", inputs=["Query"])
pipe.add_node(component=prompt_node, name="PromptNode", inputs=["MastodonFetcher"])
result = pipe.run(query="tuana@sigmoid.social", params={"MastodonFetcher": {"last_k_posts": 3}})


  1. The way this component is set up is very particular with how it expects usernames. Make sure you provide the full username, e.g.: username@instance
  2. By default, the Mastodon API allows requesting up to 40 posts.