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NFT Metadata Validator — ERC-721, OpenSea & Metaplex Preview

Validate NFT metadata against ERC-721, OpenSea, and Solana Metaplex standards. Preview your NFT before minting.

Free No signup Client-side Privacy friendly Updated

Preview

How to use

  1. 1 Pick the standard your NFT targets — ERC-721 (Ethereum), OpenSea extended, or Metaplex (Solana).
  2. 2 Paste your metadata JSON into the input panel.
  3. 3 Validation runs instantly. Fix any errors before minting.

Why use this tool

  • Catches missing required fields, malformed URLs, and non-standard attributes before you mint.
  • OpenSea-style preview card so you see exactly what collectors will see.
  • Supports IPFS CIDs (Qm… and bafy…) with auto-rewrite to a gateway for preview.
  • Runs entirely in your browser — your metadata stays private.
  • Free, no signup.

Frequently asked questions

Which standards are supported?

ERC-721 (the minimum required fields), OpenSea's extended schema (background_color, animation_url, display_type attributes), and Solana's Metaplex (symbol, properties.files, creators).

Does this guarantee my NFT will appear correctly on OpenSea?

No tool can guarantee that — OpenSea has additional indexing rules and trait normalization. But passing all checks here catches the most common rejection causes.

What about ERC-1155?

ERC-1155 metadata is identical to ERC-721 with optional {id} placeholder in URIs. Use the ERC-721 mode and validate your URI template separately.

Why does my IPFS image not load in the preview?

Cloudflare's public IPFS gateway can be slow or rate-limited for some CIDs. The metadata can still be valid even if the gateway times out.

What is NFT Metadata Validator?

An NFT Metadata Validator is a tool that checks NFT metadata for conformance to common token standards, including ERC-721, the OpenSea metadata format, and Solana's Metaplex schema. It inspects the metadata's fields and structure, reports issues, and renders a preview of how the NFT would appear before minting. It runs entirely in the browser with no account required.

Features

Three schemas

Validate against ERC-721, the OpenSea metadata extension, or Metaplex (Solana).

Image & CID checks

Verifies the image is an http(s)/ipfs/ar URL and that IPFS CIDs are well-formed.

Attribute preview

Renders the trait_type/value attributes so you see what marketplaces will display.

100% private

Runs client-side — your metadata JSON is never uploaded.

Example

Input

{"name":"Zerethon Genesis #001","description":"Genesis NFT.","image":"ipfs://QmYwAPJzv5CZsnA625s3Xf2nemtYgPpHdWEz79ojWnPbdG/1.png","attributes":[{"trait_type":"Level","value":7}]}

Output

Valid ERC-721 — 0 errors: name, image (IPFS CID ok), and attributes all pass.

Common use cases

  1. 1

    Pre-mint QA

    Validate each token's metadata before pinning it to IPFS and minting.

  2. 2

    Debug marketplace display

    Catch a missing image field or bad CID that stops a marketplace from rendering the art.

  3. 3

    Standard migration

    Check that metadata written for ERC-721 also satisfies OpenSea's optional fields.

Summary

Zerethon's NFT metadata validator checks a token metadata JSON document against the ERC-721, OpenSea, or Metaplex (Solana) schema. It flags missing or malformed fields — name, description, image URL, IPFS CID format, and the attributes array — and previews the traits, all in your browser. Nothing is uploaded.

Category
Web3
Pricing
Free
Privacy
Browser-based
Signup
Not required

References

Privacy

Your data never leaves your browser unless explicitly stated. NFT Metadata Validator runs entirely client-side — no server upload, no logging, no tracking of your input.

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