IPLD (InterPlanetary Linked Data) is a data model and set of specifications for building content-addressed, hash-linked data structures that interoperate across distributed systems. It defines how to represent linked data as directed acyclic graphs whose edges are content identifiers (CIDs), allowing any hash-linked structure — Git commits, blockchain blocks, IPFS files — to be traversed through a common addressing scheme. IPLD provides the data layer beneath IPFS and Filecoin, decoupling the logical structure of data from the protocol used to store or transport it.
Content
- IPLD generalises the insight that powers Git, Bitcoin, and IPFS alike: if you address data by the cryptographic hash of its content rather than by location, you obtain immutability, automatic deduplication, and tamper-evidence for free. IPLD formalises this into a single data model where every piece of data has a content identifier (CID) and where links between data are simply CIDs embedded in other data, forming hash-linked graphs that can span systems and protocols.
- The model is deliberately codec-agnostic. The same logical graph can be encoded as DAG-CBOR, DAG-JSON, or raw bytes, and the CID carries a multicodec prefix declaring how to interpret what it points to. This means IPLD can describe and traverse heterogeneous structures uniformly — a CID can resolve into a Git tree, an Ethereum block header, or an IPFS directory — turning previously siloed content-addressed systems into a single navigable information space.
- Because links are content hashes, IPLD graphs are necessarily directed and acyclic: you cannot reference data whose hash you do not yet know, so cycles are impossible by construction. This Merkle-DAG structure gives strong integrity guarantees — verifying the root CID transitively verifies the entire reachable graph — and enables efficient partial replication, since a consumer can fetch and validate only the subgraph it needs rather than an entire dataset.
- IPLD serves as the foundational data layer for the IPFS and Filecoin ecosystems, and its addressing model supports data availability in decentralised storage by making content location-independent and verifiable regardless of which node serves it. Its schemas and pathing conventions let applications define structured, versioned, self-verifying data formats, positioning IPLD as connective tissue for a web of interoperable, content-addressed distributed systems.