TL;DR
Librario is a pre-alpha, AGPL-licensed API that combines book metadata from multiple providers into a single response. Written in Go, it stores merged records in PostgreSQL, caches results, and serves selected cover images locally; the project is available on SourceHut for trial and contributions.
What happened
A developer launched Librario, a book-metadata aggregation API intended to address gaps between existing metadata providers. Built in Go, the service queries several third-party sources (currently Google Books, ISBNDB and Hardcover) and merges their responses into one consolidated record which is persisted in a PostgreSQL database. The project is pre-alpha, runs on a small VPS, and is distributed under the AGPL license on SourceHut. The merger logic uses extractor priorities and field-specific rules: title selection is scored to penalize parentheses and overly long strings, while cover candidates are fetched, evaluated by image quality and dimensions, and the best version is stored and served locally. Simpler fields such as publisher, language and page count take the first non-empty value by priority. A caching layer was recently added to improve speed, and the database layer is being rewritten before a 1.0 release; the maintainer has solicited feedback and patches.
Why it matters
- Consolidates fragmented book metadata into a single API response, reducing the need to query multiple services.
- Local caching and a growing PostgreSQL store mean lookups can improve over time and reduce repeated third-party queries.
- Open-source AGPL licensing allows external contributors to inspect, patch and extend the project.
- Field-specific merging rules aim to reduce incorrect or noisy metadata (for example, misattributed subtitles or low-quality covers).
Key facts
- Project name: Librario; status: pre-alpha.
- Language and tech: written in Go, persists data in PostgreSQL.
- Sources currently aggregated: Google Books, ISBNDB, Hardcover; developer indicated work on Goodreads and Anna's Archive next.
- Merger approach: each extractor has a priority and field-specific strategies are used to resolve conflicts.
- Title selection uses a scoring system that penalizes parentheses/brackets and very long titles.
- Cover handling: gathers candidate URLs, downloads and scores images by dimensions and quality, then stores the best locally and serves it.
- For many fields (publisher, language, page count) the system picks the first non-empty value by priority.
- A caching layer was recently added and improved performance for lookups.
- The original database schema was initially produced with AI assistance; maintainers hired SourceHut developers to rewrite the DB layer ahead of v1.0.
- Code is AGPL and hosted on SourceHut; the author welcomes feedback and patches.
What to watch next
- Progress and timeline for the database rewrite ahead of v1.0 (confirmed in the source).
- Integration status for Goodreads and Anna's Archive, which the developer said they are working on (confirmed in the source).
- Whether the project’s code and architecture handle third-party API rate limits and throttling under heavier traffic (not confirmed in the source).
- Long-term scalability and production-readiness beyond the current small VPS deployment (not confirmed in the source).
Quick glossary
- API: Application Programming Interface — a set of rules and endpoints that let applications request and exchange data programmatically.
- AGPL: Affero General Public License — a copyleft open-source license that requires distributing source for network-accessible software under the same license.
- PostgreSQL: An open-source relational database system commonly used to store structured application data.
- Extractor: A component that retrieves metadata from a particular external source (for example, Google Books) to be merged into a unified record.
- Caching layer: A mechanism that stores recent or computed responses to speed up subsequent requests and reduce load on upstream services.
Reader FAQ
Is Librario production-ready?
No. The project is described as pre-alpha and currently runs on a small VPS.
Where can I find the source code?
The code is available under the AGPL on SourceHut, per the project notes.
How does Librario resolve conflicting metadata?
It assigns priorities to each extractor and applies field-specific rules: titles are scored, covers are downloaded and ranked, and many simple fields use the first non-empty value by priority.
Has the service been tested against third-party rate limits?
Not confirmed in the source.
How can I try Librario?
The author provided an example curl request with an Authorization bearer token and a link to an example response for testing.
TLDR: Librario is a book metadata API that aggregates data from Google Books, ISBNDB, and Hardcover into a single response, solving the problem of no single source having complete book…
Sources
- Show HN: Librario, a book metadata API that aggregates G Books, ISBNDB, and more
- APIs
- Self-Host Weekly #153: Hivemind
- Top 9 Book APIs in 2025 – ISBNDB Blog
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