Finding Your Files in Decentralized Storage Just Got Easier
Our new CAR Content Locator solves the challenge of tracking individual files in large archives across Filecoin and IPFS networks.
At Starling Lab, we're dedicated to building tools that empower secure and verifiable data storage. Today, we're thrilled to announce the CAR Content Locator, a tool originally developed to support our Filecoin archiving work at the USC Digital Repository. With support from the IPFS Implementations Grants program, we’ve evolved this browser-based tool beyond its original purpose – tracking private files on the USC Filecoin node – into a general-purpose content locator across Filecoin and IPFS networks.
Why We Built the CAR Content Locator
As decentralized storage solutions become more prevalent, the need for robust, user-friendly tools to manage and verify content availability is critical. Our work with the USC Digital Repository highlighted a significant challenge: tracking individual files within CAR files (Content Addressable aRchives) and verifying their continued preservation without relying on public indexing services.
Organizations storing large datasets on Filecoin and IPFS face a practical problem: once dozens of files are bundled into CAR archives, how do you later find and verify specific ones?
Existing public indexing services can’t help with private or institutional data, and unfortunately our work with the USC Digital Repository – which looks after 1.2PiB+ of private archives – highlighted this challenge.
This led us to develop a tool that:
Maps file CIDs (Content Identifiers) to their locations within CAR files, especially when CAR metadata and file data exist in separate CAR files.
Extracts specific files using either a file identifier or CID across multiple CAR files.
Connects Piece CIDs and Deal IDs on the Filecoin network without requiring a full indexer.
Feature Highlights
The CAR Content Locator codebase is now published on GitHub under the MIT License, and can easily be deployed using Docker Compose. It features:
A web-based file browser that displays file integrity information (i.e. CIDs) and their availability across Filecoin and IPFS networks;
For Filecoin storage information, a Singularity-based workflow is required as it relies on its databases to keep track of Piece and Deal information;
For IPFS content availability, the tool relies on delegated routing endpoints to be available;
Although the tool is preconfigured with several public indexers, such as Pinata and Storacha, it also supports private IPFS networks, and similarly, private Filecoin nodes with the required Singularity databases.
Explore the tool in action at our demo instance!
Learnings & Next Steps
During development of the CAR Content Locator, we also conducted research on how different organizations – particularly those managing large datasets like the USC Digital Repository – address similar use cases for tracking their files across CAR-compatible networks.
We found little consistency in how users interact with Filecoin and IPFS, and workflows and toolings are usually bespoke and tailored to specific organizational needs. We hope that publishing this open source tool will also participate to the conversation on building common tooling across similar organizations.
We’d greatly appreciate your input:
Share with us how your organization tracks files stored on Filecoin and/or IPFS;
File tickets on starlinglab/car-content-locator on what features would make this tool helpful to you.
The CAR Content Locator's development has been significantly shaped by the specific needs of the USC Libraries, and it continues to keep track of its 1.2 PiB+ of private archives on their Filecoin node. Our team also works closely in parallel with the Internet Archive’ Filecoin operations.
This work is made possible by the Open Impact Foundation and the Filecoin Foundation for the Decentralized Web, as well as those who advised / contributed feedback: Mosh, Robin, Bumblefudge, Lidel, Arkadiy, Casey, Sankara, Ian, and the whole USC Digital Repository and Libraries team.