Here are reputable blockchain / decentralized-identity providers and platforms commonly used for issuing, storing, and verifying tamper‑proof credentials. Short summary + typical use cases and a source for each so you can dive deeper.

• Blockcerts (open standard) — Open-source standard and toolset for issuing blockchain‑anchored certificates (originally MIT + Learning Machine; now stewarded via Hyland/Blockcerts). Widely used by universities and governments for diplomas/transcripts. (blockcerts.org, blockcerts.learningmachine.com)

• Hyland Credentials (Learning Machine / Blockcerts implementation) — Commercial, no‑code/API product built on Blockcerts for higher‑ed and government credential issuance and verification. Good if you want an enterprise support path for Blockcerts. (hyland.com)

• Accredible — Commercial credentialing / digital-badge platform that can anchor credential records to public blockchains (used heavily by training providers, bootcamps, and certification bodies). (accredible.credential.net, accredible.com)

• Trinsic — Developer‑friendly verifiable‑credentials platform (APIs, wallets, SDKs) focused on fast integration of W3C Verifiable Credentials / DIDs for enterprise apps and developer pilots. (trinsic.id, v2-docs.trinsic.id)

• Indicio (Indicio Tech / Indicio Proven) — Enterprise-grade, open‑standards verifiable‑credentials platform for large deployments (governments, higher education, large enterprises); offers hosted and on‑prem options and wallet SDKs. (indicio.tech, docs.indicio.tech)

• Dock (Dock.io) — API platform for issuing and verifying W3C Verifiable Credentials; focuses on credential templates, issuance and Polygon/other chain integrations. Good for builders who want API-first issuance. (docs.dock.io)

• Mattr — Enterprise verifiable‑credentials and wallet solutions with strong standards support (mDocs, JSON VC formats) — used in identity and government/enterprise scenarios. (auth0.com, learn.mattr.global)

• Transmute — Verifiable Data / credential platform oriented to supply‑chain and trade workflows; focuses on interoperability and enterprise integration. (medium.com, guide.transmute.industries)

• Spruce (SpruceID) — Open‑source toolkits and wallet/SDKs (DIDKit, Credible) for developers building DID/VC workflows; good for projects that want open toolchains and audits. (blog.spruceid.com)

• Serto / Veramo (uPort successors) — Developer frameworks and services evolving from uPort; Veramo is a popular JavaScript SDK for building DID/VC apps; Serto provides enterprise APIs. Good choices for bespoke, framework‑based development. (serto.medium.com, decentralized-id.com)

• KILT Protocol — A blockchain protocol for issuing self‑sovereign, revocable credentials (Polkadot ecosystem); useful when you want on‑chain attestation/revocation models and Web3-native credentials. (docs.kilt.io)

• Turing Certs — Blockchain‑anchored academic credentialing (uses IOTA/Shimmer in some deployments); used by some institutions for diploma/transcript issuance. (turingcerts.com)

Quick selection tips

• Look for W3C Verifiable Credentials and DID support if you want interoperability. (Most vendors above support these standards.) (trinsic.id, microsoft.com)
• For higher education/government: Blockcerts/Hyland, Accredible, Indicio are common choices. (blockcerts.org, hyland.com, accredible.credential.net)
• For developer-first / prototype builds: Trinsic, Veramo, Spruce, Dock. (trinsic.id, decentralized-id.com, blog.spruceid.com, docs.dock.io)
• For Web3-native or protocol-level needs: KILT, Transmute, Turing Certs. (docs.kilt.io, medium.com, turingcerts.com)

If you’d like, I can:

• narrow this to the top 3 choices for a specific use case (university diplomas, corporate HR verification, supply‑chain trade documents, developer POC), or
• create a short vendor‑comparison table (standards, on‑chain vs off‑chain storage, wallet support, typical pricing model).