What is Libraries.io?

Updated

Libraries.io is a free service for discovering open source packages. It collects publicly available package information scraped from the internet and lets you search across millions of packages by license, language, and other criteria. It's useful for general exploration — finding packages, checking what's out there, and browsing trends — but its data is not validated for accuracy, so it isn't the right tool for making important decisions about open source usage and management.

What Libraries.io covers

According to the site, Libraries.io monitors 11,927,330 open source packages across 32 different package managers, and you can search 9.96M packages by license or language. Beyond search, it offers ways to explore new, trending, or popular packages.

The core capabilities:

  • Search packages by license, language, or keyword
  • Explore new, trending, and popular packages
  • Browse metadata read from package and source repository metadata
  • Access an API (documentation is available after login)

How the data is collected — and its limits

Libraries.io describes itself as a free service that collects publicly available open source package information scraped from the internet. The site states plainly that this data is not validated, corrected, or curated for accuracy.

That distinction matters. Package metadata and license data are read from package and source repository metadata rather than verified. Dependency insights are described as limited and not validated for accuracy. Vulnerability insights are not included at all.

So the practical rule: use Libraries.io for discovery and orientation, not as the authoritative source for compliance, security, or dependency decisions.

Libraries.io vs. the Tidelift Subscription

The site positions a paid offering — the Tidelift Subscription — as the option for "more complete and accurate package data," aimed at people making important decisions about open source usage and management. The comparison table on Libraries.io lays out the differences:

Dimension Libraries.io Tidelift Subscription
Package metadata Read from package and source repository metadata, not validated for accuracy Extensive and human-validated for accuracy
Secure development practices Not included Pays maintainers to implement secure development practices and provide attestations (e.g., 2FA status, security policy)
License data Read from package metadata, not validated for accuracy Analyzed and manually validated, including normalized SPDX expressions
Dependency insights Limited, not validated for accuracy Extensive, human-validated, including dependency graph relationships
Vulnerability insights Not included CVE data ingested from multiple sources, mapped to specific versions, plus maintainer CVE reviews

The Tidelift Subscription is also described as providing deeper insights for evaluating latent risk indicators such as package maintenance and end-of-life status, and for evaluating code contributors and security measures like two-factor authentication.

Which one fits your task

  • Choose Libraries.io if you want free, broad discovery: searching packages by license or language, exploring what's new or trending, or pulling package metadata for general reference.
  • Consider the Tidelift Subscription if you need validated license data, dependency graph relationships, vulnerability data mapped to specific versions, or signals about maintainer practices — the kind of inputs that feed into compliance, security, or open source management decisions.

The site itself frames the split this way: Libraries.io is a free service for browsing scraped public data, while the Tidelift Subscription is the paid, curated source backed by Tidelift and its maintainer partners.

Getting started

Libraries.io requires a login to use. You can sign in with GitHub, GitLab, or Bitbucket, and by logging in you accept the site's terms of service and privacy policy. API documentation is available once you're logged in.

One note worth flagging: the site displays a banner stating that Sonar has entered a definitive agreement to acquire Tidelift. If you're evaluating these services for a longer-term commitment, that's a change worth tracking.