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Photon is Light Protocol's open-source indexer service that continuously reads Solana's transaction logs and ledger to reconstruct the full state of compressed accounts and Concurrent Merkle Trees, making this off-chain data queryable via a JSON-RPC API that mirrors the standard Solana RPC interface with additional ZK-compression-specific methods. Because compressed account data is not stored in on-chain account space but is instead emitted during transactions as instruction data and logs, a dedicated indexer like Photon is required for clients to fetch account state, generate Merkle proofs, and construct valid transactions that interact with compressed accounts. Photon exposes methods such as getCompressedAccount, getCompressedTokenAccountsByOwner, and getValidityProof, and Light Protocol operates a hosted Photon endpoint while teams can also self-host it against their own RPC node.

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Compressed state, proofs, and scale-oriented storage patterns.

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Photon Indexer (photon-indexer)
Category: ZK Compression
Definition: Photon is Light Protocol's open-source indexer service that continuously reads Solana's transaction logs and ledger to reconstruct the full state of compressed accounts and Concurrent Merkle Trees, making this off-chain data queryable via a JSON-RPC API that mirrors the standard Solana RPC interface with additional ZK-compression-specific methods. Because compressed account data is not stored in on-chain account space but is instead emitted during transactions as instruction data and logs, a dedicated indexer like Photon is required for clients to fetch account state, generate Merkle proofs, and construct valid transactions that interact with compressed accounts. Photon exposes methods such as getCompressedAccount, getCompressedTokenAccountsByOwner, and getValidityProof, and Light Protocol operates a hosted Photon endpoint while teams can also self-host it against their own RPC node.
Related: ZK Compression, Indexer

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ZK Compression

ZK Compression, pioneered by Light Protocol, extends Solana's state compression model beyond NFTs to general-purpose compressed accounts by using zero-knowledge proofs (specifically Groth16 SNARKs verified via the alt_bn128 syscall) to prove the validity of state transitions without storing full account state on-chain. Compressed accounts live in on-chain Merkle trees but their data is reconstructed from the Solana ledger by indexers like Photon, enabling developers to build applications that use thousands of accounts at a fraction of the normal rent cost — often 1,000x to 5,000x cheaper than regular accounts. The protocol introduces compressed tokens, compressed PDAs, and a system of nullifiers to prevent double-spends while maintaining Solana's throughput.

State Compression Compressed Account

Open term

Branch

Indexer

A specialized off-chain service that continuously ingests on-chain data (typically via a Geyser plugin or RPC polling) and stores it in a queryable database optimized for complex lookups, aggregations, and historical queries that the RPC node's account-state store cannot efficiently serve. Indexers power DAS APIs, portfolio trackers, analytics dashboards, and DEX order-history features by transforming Solana's append-only ledger into relational or document-oriented schemas with fast secondary indexes.

Geyser Plugin DAS (Digital Asset Standard) API

Open term

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ZK Compression

ZK Compression, pioneered by Light Protocol, extends Solana's state compression model beyond NFTs to general-purpose compressed accounts by using zero-knowledge proofs (specifically Groth16 SNARKs verified via the alt_bn128 syscall) to prove the validity of state transitions without storing full account state on-chain. Compressed accounts live in on-chain Merkle trees but their data is reconstructed from the Solana ledger by indexers like Photon, enabling developers to build applications that use thousands of accounts at a fraction of the normal rent cost — often 1,000x to 5,000x cheaper than regular accounts. The protocol introduces compressed tokens, compressed PDAs, and a system of nullifiers to prevent double-spends while maintaining Solana's throughput.

Open term

Infrastructure

Indexer

A specialized off-chain service that continuously ingests on-chain data (typically via a Geyser plugin or RPC polling) and stores it in a queryable database optimized for complex lookups, aggregations, and historical queries that the RPC node's account-state store cannot efficiently serve. Indexers power DAS APIs, portfolio trackers, analytics dashboards, and DEX order-history features by transforming Solana's append-only ledger into relational or document-oriented schemas with fast secondary indexes.

Open term

ZK Compression

PLONK

PLONK (Permutations over Lagrange-bases for Oecumenical Noninteractive arguments of Knowledge) is a universal zk-SNARK proving system that requires only a single, circuit-agnostic trusted setup (a universal SRS), eliminating the need for per-circuit ceremonies required by systems like Groth16, while producing proofs that are slightly larger but allow circuits to be updated or added without new ceremonies. PLONK-based systems (including its variants Turbo-PLONK and Ultra-PLONK used by protocols like Aztec) support custom gates and lookup tables, enabling more efficient encoding of operations like range checks and hash functions in arithmetic circuits. On Solana, PLONK is less commonly deployed for on-chain verification than Groth16 because verification is more compute-intensive, but it is used off-chain in toolchains and protocol designs targeting future SVM upgrades with broader syscall support.

Open term

ZK Compression

Nullifier

A nullifier is a cryptographic value derived deterministically from a compressed account's leaf hash (and optionally a secret) that is published and recorded on-chain when that compressed account is consumed (spent) in a state transition, permanently marking the account as used and preventing it from being spent a second time in a double-spend attack. In Light Protocol, nullifiers are inserted into an on-chain nullifier queue account and periodically batch-processed by Forester nodes into a nullifier set stored in a separate Merkle tree, allowing the validity proof to assert both that the input account exists (inclusion proof) and that its nullifier has not yet been recorded (non-membership proof). The nullifier scheme allows compressed accounts to be treated as UTXOs — each account is consumed once and replaced by one or more output accounts — while maintaining the privacy and succinctness properties of the ZK proof system.

Open term

Related terms

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ZK Compressionzk-compression

ZK Compression

ZK Compression, pioneered by Light Protocol, extends Solana's state compression model beyond NFTs to general-purpose compressed accounts by using zero-knowledge proofs (specifically Groth16 SNARKs verified via the alt_bn128 syscall) to prove the validity of state transitions without storing full account state on-chain. Compressed accounts live in on-chain Merkle trees but their data is reconstructed from the Solana ledger by indexers like Photon, enabling developers to build applications that use thousands of accounts at a fraction of the normal rent cost — often 1,000x to 5,000x cheaper than regular accounts. The protocol introduces compressed tokens, compressed PDAs, and a system of nullifiers to prevent double-spends while maintaining Solana's throughput.

Open term

Infrastructureindexer

Indexer

A specialized off-chain service that continuously ingests on-chain data (typically via a Geyser plugin or RPC polling) and stores it in a queryable database optimized for complex lookups, aggregations, and historical queries that the RPC node's account-state store cannot efficiently serve. Indexers power DAS APIs, portfolio trackers, analytics dashboards, and DEX order-history features by transforming Solana's append-only ledger into relational or document-oriented schemas with fast secondary indexes.

Open term

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ZK Compression

State Compression

State Compression is Solana's technique for storing the cryptographic fingerprint (root hash) of a Merkle tree on-chain while keeping the actual leaf data off-chain in the Solana ledger's account data logs, reducing the cost of storing large datasets by orders of magnitude. A compressed NFT collection of 1 million items costs roughly 50 SOL to mint versus ~12,000 SOL with standard SPL accounts, because only a single Concurrent Merkle Tree account occupies on-chain storage. Any data change requires updating the root hash and supplying a Merkle proof to the on-chain program, which verifies inclusion without reading the full dataset.

Open term

ZK Compression

ZK Compression, pioneered by Light Protocol, extends Solana's state compression model beyond NFTs to general-purpose compressed accounts by using zero-knowledge proofs (specifically Groth16 SNARKs verified via the alt_bn128 syscall) to prove the validity of state transitions without storing full account state on-chain. Compressed accounts live in on-chain Merkle trees but their data is reconstructed from the Solana ledger by indexers like Photon, enabling developers to build applications that use thousands of accounts at a fraction of the normal rent cost — often 1,000x to 5,000x cheaper than regular accounts. The protocol introduces compressed tokens, compressed PDAs, and a system of nullifiers to prevent double-spends while maintaining Solana's throughput.

Open term

ZK Compression

Compressed Account

A compressed account is a Solana account whose state is stored as a leaf in an on-chain Concurrent Merkle Tree rather than as a dedicated on-chain account, making it 100–1,000x cheaper to create and maintain because no rent-exempt lamport balance is required per account. Compressed accounts are identified by a hash of their data and position in the tree; to interact with one, a client must supply a Merkle proof (or rely on the canopy) showing the leaf is part of the current tree root, which the on-chain program verifies before processing the state change. Light Protocol's compressed account model supports arbitrary data, discriminators, and owner programs, making it a general-purpose replacement for expensive on-chain accounts in high-volume use cases.

Open term

ZK Compression

Concurrent Merkle Tree

A Concurrent Merkle Tree (CMT) is a specialized on-chain Solana data structure that allows multiple state updates to the same Merkle tree within a single block without conflicting, by recording a changelog buffer of recent root transitions that validators use to reconcile parallel proof submissions. A CMT is parameterized by its maximum depth (max_depth, determining tree capacity of 2^max_depth leaves), max_buffer_size (number of concurrent changes the changelog can track, directly controlling how many operations per slot the tree can safely absorb), and an optional canopy_depth. The SPL Account Compression program manages CMTs, and they are the foundational storage primitive for both Metaplex compressed NFTs and Light Protocol compressed accounts.

Open term