Search for newsletters by topic, title, or author across Substack, LinkedIn, Ghost, Beehiiv and Kit. Returns subscriber numbers per publication. Specify either query or filters or both. Filters are comma-separated, e.g. subscribers:gte:5000,active:is:true,platforms:any:substack-beehiiv-kit. Full filter reference: https://reletter.com/developers/search-filters

Search across the body and titles of every newsletter issue Reletter has indexed. Returns highlighted snippets when highlight=true. Accepts the same filters parameter as search_publications; filters apply to the parent publication.

Returns suggested keywords and matching newsletters for a search query.

Look up full metadata for a newsletter by its Reletter slug, e.g. 'doomberg'. Includes subscribers, engagement, social, contributors, recent issues, rankings, and SEO reach (Google search keywords and estimated traffic).

List the 100 most recent issues for a publication in reverse chronological order.

Full data for a single issue, including the body text and the publication it belongs to.

Email contacts, contact pages, and social accounts for a newsletter. Includes contributors where Reletter has identified them.

List available chart platforms and categories.

Latest chart rankings for a platform / category. Use chart_categories to discover valid platform and category slugs.

List every language. Codes are used with the languages search filter.

Global Reletter index stats: total publications, issues, etc.

Check your API request quota and usage for the current month.