Verifiable Data, Verifiable Data Feed, Verifiable Data Package, and Verifiable Data Services: A Complete Guide

Description: A practical, decision-maker’s guide to designing, buying, and integrating verifiable off-chain and cross-chain data into production blockchain systems in 2026, with concrete architectures, emerging standards, and field-tested implementation patterns.

TL;DR (for busy leaders)

Verifiable data is no longer “nice to have.” With VC 2.0 now a W3C Standard and low‑latency oracle products maturing across 100+ chains, you can design end‑to‑end verifiability—data origin, transport, proofs, and on‑chain verification—without tolerating opaque trust gaps. (w3.org)
The fastest path to production combines Verifiable Data Packages (VDPs) with a fit‑for‑purpose delivery pattern: low‑latency signed reports (e.g., Chainlink Data Streams), pull‑based signed updates (e.g., Pyth Core), optimistic assertions (UMA), or first‑party dAPIs (API3). Anchor large artifacts using EIP‑4844 blobs + long‑term storage and validate everything on‑chain. (docs.chain.link)

Who should read this

Startup founders building DeFi, payments, or real‑world assets (RWA) who must reduce oracle risk while meeting latency and cost targets.
Enterprise leaders moving data on‑chain for compliance/transparency and needing verifiable identity, provenance, and auditability.

Clear definitions (no fluff)

Verifiable Data (VD): Any data element whose origin, integrity, and freshness can be validated cryptographically by your smart contracts or off‑chain verifiers. Examples: price ticks, fund NAV snapshots, emissions readings, KYC claims, or historical L1 state proofs.
Verifiable Data Feed (VDF): A continuously updated stream of verifiable data (e.g., prices, reserves, macro metrics) published on‑chain or off‑chain with on‑chain verification hooks. Examples: Chainlink Data Feeds/Streams; Pyth Core/Pro; API3 dAPIs. (data.chain.link)
Verifiable Data Package (VDP): A compact, tamper‑evident bundle that carries your payload + schema + provenance + attestations + anchors so contracts can verify authenticity/freshness deterministically. Think “self‑describing, signature‑backed container” you can store, relay, and check years later. (7blocklabs.com)
Verifiable Data Services (VDS): Managed services supplying verifiable compute, verification, and attestations: e.g., Chainlink Proof of Reserve, Automation 2.0 verifiable compute, storage‑proof providers (Herodotus), zk coprocessors (Lagrange), and web‑data attestation (TLSNotary/zkTLS). (data.chain.link)

Why this matters in 2026

Identity and credentials: The Verifiable Credentials Data Model v2.0 became a W3C Recommendation on May 15, 2025, solidifying interoperable formats for credential issuance and verification across industries. This enables composable identity/data exchange between wallets, APIs, and smart contracts. (w3.org)
Low‑latency, high‑coverage feeds: Oracle networks now support 100+ chains with sub‑second or ~400 ms data updates and on‑demand verification paths, closing the UX gap to centralized markets. (docs.pyth.network)
Cheap, anchorable data availability: EIP‑4844 (blobs) gives you cheap, ephemeral data space with KZG commitments accessible to EVM via a precompile—ideal for anchoring VDP commitments and proving correspondence later. (eips.ethereum.org)

The anatomy of a Verifiable Data Package (VDP)

At minimum, design your VDP to include:

Header: version, schema ID, data source IDs/URIs, timestamp, chainId, nonce/sequence, expiration.
Payload: typed domain data (e.g., “ETH/USD mid at 3:03:20.123 UTC; VWAP method; venue set CBOE/CME/Kraken”).
Provenance: how data was collected, jurisdiction/licensing, method parameters.
Attestations:
- Signatures from issuers/oracle nodes (ECDSA or BLS aggregate).
- Commitments (Merkle/KZG) for batch inclusion proofs.
- Optional ZK proof (e.g., Proof‑of‑SQL or custom circuit) for computation correctness.
Anchors: CID/TxID/DA certificate and, when possible, EIP‑4844 commitment/versioned hash for on‑chain accessible integrity. (7blocklabs.com)

Example (illustrative JSON):

{
  "vdp_version": "1.2.0",
  "schema": "com.example.nav.v1",
  "payload": {
    "instrument": "RWA-FUND-A",
    "nav": "102.3845",
    "currency": "USD",
    "asof_ms": 1765753200123,
    "method": "T+0_endofday_GAAP"
  },
  "provenance": {
    "collectors": ["did:web:data.vendor.example"],
    "jurisdiction": "US",
    "license": "CC-BY-4.0"
  },
  "attestations": {
    "signers": [
      {"kid": "did:pkh:eip155:1:0xabc...", "alg": "secp256k1", "sig": "0x..."},
      {"kid": "did:pkh:eip155:1:0xdef...", "alg": "secp256k1", "sig": "0x..."}
    ],
    "commitment": {
      "type": "kzg",
      "blob_versioned_hash": "0x01...31bytes",
      "proof": "0x...48bytes"
    }
  },
  "anchors": {
    "eip4844": {"txHash": "0x...", "index": 0},
    "ipfs": "bafy...",
    "arweave_tx": "bT2...q7E"
  },
  "policy": {
    "staleness_s": 30,
    "threshold_m_of_n": "2-of-3",
    "replay_domain": "mainnet:perps-v3"
  }
}

Notes:

KZG commitments from EIP‑4844 are succinct (48‑byte commitments) and verifiable via the point‑evaluation precompile, letting your contract verify specific field evaluations against the committed blob. Blobs are pruned (~18 days), so also re‑anchor to long‑term storage for audits. (eips.ethereum.org)

Delivery patterns: pick the right one for your latency, cost, and trust model

Low‑latency signed reports with on‑chain verification (example: Chainlink Data Streams)

What: Fetch high‑frequency signed reports over REST/WebSocket; verify them on‑chain via a Verifier Proxy contract deployed per network; settle with low latency and predictable fees/SLAs. SDKs exist for Go/Rust/TS. Supported across many L1s/L2s (e.g., opBNB, Sei; native precompile on MegaETH). (docs.chain.link)
When to use: Perps and options venues, stablecoins with tight peg monitors, prediction markets needing sub‑second deltas.
Practical tip: Put a staleness window and multi‑feed fallback; verify report signatures and schema version before state changes.

Pull‑based signed updates with on‑demand verification (example: Pyth Core)

What: Users fetch signed update payloads from Hermes (REST/SSE) and submit them in‑tx; contracts verify Wormhole‑signed Merkle roots and inclusion proofs before updating on‑chain price. Pyth Core targets ~400 ms updates, 120+ first‑party providers, and >100 blockchains. (docs.pyth.network)
When to use: Latency-sensitive apps that want control over when they pay to update (only when executing).
Practical tip: Enforce “update then read” design; fail closed on stale reads using getPriceNoOlderThan or equivalent guardrails. (docs.pyth.network)

Optimistic assertions (example: UMA Optimistic Oracle)

What: A proposer posts a claim with a bond; if undisputed within a liveness window, the claim finalizes. Disputes go to tokenholder voting/arbitration. (docs.uma.xyz)
When to use: Human‑interpretable truths, long‑tail data, or governance operations (e.g., oSnap: off‑chain Snapshot vote executed on‑chain after UMA verification). (docs.uma.xyz)

First‑party dAPIs and direct Airnode (example: API3)

What: API providers run Airnode (serverless, “set‑and‑forget”) and sign data at the source; dAPIs aggregate first‑party feeds into on‑chain values you can consume across 39+ chains. Managed dAPIs can be paid in native gas token. (airnode-docs.api3.org)
When to use: You want end‑to‑end source transparency and first‑party signatures with minimal middleware.

Signed calldata packages (example: RedStone)

What: Attach signed “data packages” to calldata only when needed; contracts verify signer set, timestamps, then extract values in a gas‑optimized flow. Deployed across 100+ chains. (github.com)

Verifiable Data Feeds you can buy today

Chainlink Data Feeds: Broad coverage (crypto, fiat, commodities, RWAs, proof‑of‑reserve, equity/ETF/NAV) across 25+ mainnets; feeds include market‑hours guidance for non‑24/7 instruments—use feed‑appropriate trading windows. (data.chain.link)
Chainlink Data Streams: Low‑latency reports with on‑chain verification; 99.9%+ uptime targets; multi‑site aggregation; SDKs for Go/Rust/TS; verifier proxies per network. (docs.chain.link)
Pyth Core/Pro: Core offers decentralized, deterministic on‑chain delivery and ~400 ms update frequency; Pro adds ultra‑low‑latency channels and equities/indexes; Hermes provides REST/SSE for updates. (docs.pyth.network)
API3 dAPIs: First‑party signed feeds aggregated on‑chain, with Managed dAPIs operated by the API3 DAO and fallbacks; developers pay in native gas token and inspect underlying beacons and endpoints. (blog.api3.org)

Verifiable Data Services: compute, attest, and prove

Chainlink Proof of Reserve (PoR): Automated on‑chain audits of reserves with independent attestation/verification best practices; integrate circuit‑breaker logic tied to PoR feeds. (blog.chain.link)
Chainlink Automation 2.0 (Verifiable Compute): Offload Solidity logic to OCR 3.0 consensus; reports are signed and verified before execution; up to ~10x gas savings and 10M gas off‑chain compute per job. (blog.chain.link)
Storage proofs and ZK coprocessors:
- Herodotus: Storage Proofs and historical block accumulators to verify cross‑chain/historical state with ZK proofs; APIs and “Turbo” simplify integration. (docs.herodotus.dev)
- Lagrange: ZK coprocessor with verifiable database + prover network for scalable SQL‑like queries over large chain datasets. (lagrange.dev)
- Note: Axiom V2 (historic state ZK coprocessor) went live in 2024 but was later deprecated as the team shifted to OpenVM—illustrating vendor lifecycle risk to plan for. (blog.axiom.xyz)
Web‑data attestation (TLSNotary / zkTLS): Produce portable proofs that specific HTTPS content came from a given origin, enabling verifiable web‑to‑chain facts (e.g., bank balance proof) without server changes; active community and workshops across 2024–2025. (tlsnotary.org)
Attestations as a primitive (EAS): Ethereum Attestation Service provides on‑/off‑chain attestations and schema registry, with millions of attestations across L2s—useful to express policy, eligibility, and provenance alongside VDPs. (attest.org)

Practical blueprints you can copy

RWA fund NAV with end‑to‑end verifiability

Data producers compute NAV and emit a VDP signed by 2‑of‑3 signers; also post a blob (EIP‑4844) of the day’s portfolio snapshot, storing the versioned hash on‑chain. Re‑anchor full detail to IPFS/Arweave for audits.
Delivery: Post VDP to a Streams‑like service for sub‑second updates during trading hours; for daily closing NAV, publish to a (slower) on‑chain Data Feed and PoR feed for custodied assets.
On‑chain: Verify the report via the network’s Verifier contract; check staleness_s and schema version. If out of bounds, fail closed or fall back to yesterday’s finalized NAV with an event.
Compliance: Require a W3C VC 2.0 “Accredited Investor” credential and an EAS attestation for jurisdictional eligibility before allowing primary issuance. (docs.chain.link)
Auditability: For disputes, the contract exposes the blob versioned hash; auditors retrieve the blob, verify KZG proof against the versioned hash, and reconcile to off‑chain reports. (eips.ethereum.org)

Perps DEX with CEX‑like UX and provable data

Use Chainlink Data Streams for sub‑second mid/LWBA prices; verify each report on‑chain before funding rate or liquidation steps. Deploy on supported networks (e.g., opBNB, Sei; native on MegaETH) for latency parity with CEXs. (prnewswire.com)
Add Pyth Core as a pull‑based backup with Hermes; on liquidation, require a second signed update within N seconds or revert. (docs.pyth.network)
Off‑chain compute: Use Automation 2.0 verifiable compute for path‑dependent risk checks and batch order matching to cut gas. (blog.chain.link)

KYB/KYC‑gated DeFi facility

Identity: Issue W3C VC 2.0 credentials through your provider; holders present ZK‑selective disclosure off‑chain, and the verifier emits an EAS attestation UID for on‑chain gating. (w3.org)
Runtime: Smart contracts check EAS schema UIDs and expiration; if present and fresh, enable higher LTV or credit limits. (easscan.org)
Proof of reserves/collateral: Subscribe to a PoR feed for the custodian account and wire alerts into Automation‑triggered circuit breakers. (data.chain.link)

Emerging best practices (2026 edition)

Schema rigor: Tie every VDP/VDF to a versioned schema (JSON‑Schema, SSZ, Cap’n Proto). Treat schema changes as breaking; migrate with deprecation windows.
Anchoring strategy:
- Short‑term: EIP‑4844 blob commitments for cheap inclusion + on‑chain accessible hashes.
- Long‑term: IPFS/Arweave/DA certificates for years‑later audits. Document retrieval+proof steps in runbooks. (eips.ethereum.org)
Latency budget by product:
- Derivatives: sub‑second streams + on‑chain verify;
- Lending: seconds‑level feeds with hysteresis, signed twaps;
- RWA NAV: daily finalized with blob anchors and audit trail.
Defense in depth:
- Multiple independent providers/networks (Streams + Pyth pull; or dAPIs + RedStone fallback).
- Different proof roots (signature sets vs Merkle/KZG vs ZK), so that a single class of failure can’t invalidate everything. (docs.chain.link)
Responsible market‑hours handling: For equities/commodities, enforce feed‑specific trading windows (e.g., US equities 09:30–16:00 ET), or tighten risk parameters out of hours. (docs.chain.link)
Provenance and licensing: Carry license/jurisdiction in the VDP and verify origin claims (DIDs, TLSNotary for web sources) before accepting data. (tlsnotary.org)
Observability and SLAs: Use on‑chain verifiers’ addresses per network (documented by vendors) and monitor staleness, signature quorums, and update fees. Aim for 99.9%+ availability where product‑critical. (docs.chain.link)
Governance and revocation: Support key rotation, signer quorum changes, schema deprecation, and VC revocation lists (Bitstring Status List v1.0 for credentials ecosystems). (w3.org)

Build vs. buy: a concrete decision frame

Buy a VDF/VDS when:
- Latency/uptime requirements are strict (perps/options).
- Compliance needs independent attestation (PoR, regulated data).
- You lack team bandwidth for ops (24/7 DevOps and key management). (chain.link)
Build/augment with VDPs when:
- You own proprietary signals (e.g., NAV, IoT telemetry) and need custom schema/provenance.
- You want hybrid delivery (Streams for trading, blobs for audit, EAS/VC for access control).
- You need to combine on‑chain state proofs (Herodotus/Lagrange) with off‑chain or web proofs (TLSNotary). (docs.herodotus.dev)

Cost drivers to model:

Data updates: pull vs push (you pay only when you use with pull models like Pyth Core). (docs.pyth.network)
On‑chain verification: per‑report verification and gas; consider batching updates and using KZG commitments for inclusion proofs. (eips.ethereum.org)
Ops and key management: signer rotation, HSMs/threshold‑signing, audit logging.

Implementation checklist (copy/paste into your runbook)

Define the truth you need

Metric, units, frequency, acceptable staleness, allowed venues/sources.

Choose delivery pattern(s)

Streams (low latency), pull updates (on demand), optimistic (human‑in‑the‑loop), first‑party dAPIs, or signed calldata packages. Combine at least two for resilience. (docs.chain.link)

Specify your VDP

Schema ID and version; provenance fields; policy (m‑of‑n signers, staleness_s); anchors (EIP‑4844 + IPFS/Arweave). (eips.ethereum.org)

On‑chain verification

Integrate vendor verifier proxies; implement staleness checks and schema guards; emit events with versioned hashes/CIDs for audits. (docs.chain.link)

Identity and permissions

If gating access/limits: accept W3C VC 2.0 credentials off‑chain, mint/rely on EAS attestations on‑chain, and enforce expiration/revocation. (w3.org)

Observability and DR

Dashboards for heartbeat/staleness; CIRCUIT_BREAKER() tied to PoR feeds or price deviation; fallback to secondary feed or safe mode. (data.chain.link)

Audits and compliance

Maintain retrievability of VDP artifacts beyond blob retention window; test KZG proofs against versioned hashes; archive signer key rotations and schema migrations. (finematics.com)

Brief deep dive: three critical building blocks you’ll use

EIP‑4844 blob commitments
- 128 KB blobs; 48‑byte KZG commitments; point‑evaluation precompile for verification; blobs pruned after ~18 days—cheap enough for routine anchoring, but plan secondary storage. (eips.ethereum.org)
Pyth Hermes update flow
- Clients fetch latest updates via REST or SSE; submit to chain with update fees; contract verifies Wormhole‑signed Merkle root and per‑feed proofs, then writes storage. Great for “update‑then‑settle” transactions. (docs.pyth.network)
Chainlink Automation 2.0 verifiable compute
- OCR 3.0 quorum signs performData; Registry verifies before execution; offload heavy math and multi‑vault loops; measured 10x gas savings in some vault flows. (blog.chain.link)

Common pitfalls we see (and how to avoid them)

Relying on one oracle or one proof system: Build cross‑vendor redundancy and cross‑proof verification (e.g., Streams + Pyth pull, or dAPIs + RedStone). (docs.chain.link)
Ignoring market hours: Using equity/commodity feeds outside specified hours inflates risk; tie trading logic to feed market‑hours metadata. (docs.chain.link)
Forgetting long‑term auditability: Blobs expire; without IPFS/Arweave/DA re‑anchor, you’ll lose the evidence chain. (finematics.com)
Conflating identity with entitlement: Accepting a “KYC passed” VC off‑chain is not enough; persist an on‑chain attestation (EAS) with expiration and policy schema for deterministic enforcement. (easscan.org)

The road ahead

Identity/data convergence: VC 2.0 plus on‑chain attestations will make policy‑driven markets mainstream (eligibility, geography, risk scores) without sacrificing privacy. (w3.org)
Native low‑latency markets: Data Streams‑style precompiles and pervasive off‑chain verification will unlock real‑time DeFi on emerging real‑time L1s. (megaeth.com)
Verifiable web data: zkTLS/TLSNotary will connect Web2 sources to Web3 contracts, enabling automated compliance, credit, and commerce with portable proofs. (tlsnotary.org)

Final take

If you’re evaluating blockchain solutions in 2026, anchor your architecture around verifiability, not just “oracle access.” Standardize on VDPs; select at least two delivery patterns; anchor with EIP‑4844; wire in identity/attestation; and outsource compute where it’s verifiable. The upside is better UX, lower risk, audit‑readiness, and fewer surprises in production.

Need help designing, implementing, or auditing your verifiable data stack? 7Block Labs can blueprint, build, and run it with you.