One example is that Claude has supported creating Artifacts for some time now: https://www.anthropic.com/news/artifacts
A quick Kagi search came up with this as the top result:
Langchain AI Open Canvas: https://github.com/langchain-ai/open-canvas
What kind of editor do you mean? E.g. a document or code editor?
Three similar options would be:
Google Docs with Gemini: https://support.google.com/docs/answer/14355406
Affine AI: https://affine.pro/
Notion AI: https://www.notion.com/help/guides/category/ai