IPFS Gateway

An IPFS Gateway translates HTTP requests (like https://gateway.example.com/ipfs/QmHash...) into requests for content identifiers (CIDs) on the IPFS network. This allows any standard web browser or API client to retrieve immutable, verifiable content without running a local IPFS node. The gateway resolves the CID, fetches the content from the distributed network, and serves it over HTTPS.

The gateway acts as a protocol bridge, converting between:

• HTTP/HTTPS (the web's protocol) and libp2p (IPFS's networking stack).
• Location-based addressing (URLs) and content-based addressing (CIDs). This interoperability is crucial for dApp frontends, NFT marketplaces, and decentralized websites to function seamlessly for users on traditional browsers.

Gateways implement caching layers to improve performance and reduce network load. Key strategies include:

• Edge Caching: Storing frequently requested content at geographically distributed edge servers for low-latency delivery.
• Pinning Services: Some gateways integrate with pinning services to ensure popular content remains highly available.
• This transforms the potentially slow initial retrieval from a peer-to-peer network into a fast, CDN-like experience for end-users.

Gateways support different URL schemas for accessing content:

• Path Gateway: https://gateway.ipfs.io/ipfs/QmHash... (Legacy, less secure for active content).
• Subdomain Gateway: https://QmHash.ipfs.gateway.io/ (Modern standard). Subdomain isolation provides origin security, allowing modern web features (Service Workers, HTTP/2) to function correctly with decentralized content.
• DNSLink Gateway: https://example.com can resolve to IPFS content via a DNS TXT record, enabling human-readable names.

Gateways exist on a spectrum from centralized to decentralized:

• Public Gateways: Operated by entities like Cloudflare, Protocol Labs, or community members. They are convenient but introduce a point of trust.
• Dedicated/Private Gateways: Run by dApps or organizations for their specific content, reducing reliance on public infrastructure.
• Local Gateway: Part of a Kubo (go-ipfs) or Helia node, providing direct, trustless access to the IPFS network from a user's own machine.

Beyond read-only access, some gateways offer write endpoints, allowing users to add content to IPFS via HTTP. This is typically done by:

• POSTing files to a gateway endpoint, which pins the content and returns the generated CID.
• Integrating with services like IPFS Cluster for managed pinning and replication.
• This feature enables serverless backends and applications to persist data directly to the decentralized web.

Beyond simple retrieval, gateways enable cryptographic verification. The CID in the gateway URL is a hash of the content. Any user or client can fetch the data and recompute the hash to verify it matches the CID, ensuring the data has not been altered.

• Trust Minimization: This provides end-to-end integrity between the publisher and the end-user, even when using a third-party gateway.

Gateways perform essential protocol translation between HTTP (location-based) and IPFS (content-based) paradigms. They handle:

• Path Gateway Style: /ipfs/<CID>/path/to/file
• Subdomain Gateway Style: <CID>.ipfs.<gateway-host>.com
• DNSLink Resolution: Mapping a human-readable domain (e.g., docs.ipfs.tech) to an IPFS address. This abstraction is key to mainstream adoption without requiring users to install special software.

Using a public gateway reintroduces a central point of failure and trust. The gateway operator can:

• Censor or block access to specific content.
• Log user requests and metadata (IP addresses, timestamps).
• Serve modified content if not properly validating hashes. This contrasts with the trustless model of running a local IPFS node. For sensitive data, self-hosting a gateway or using a decentralized gateway network is recommended.

The Content Identifier (CID) is a cryptographic hash of the content. A reliable gateway ensures content-addressed integrity:

• The gateway fetches data from the IPFS network using the CID.
• Users must verify the served content matches the expected CID hash.
• Immutability is guaranteed only if the CID is pinned and available on the network; gateways cannot serve data that doesn't exist on IPFS. A critical risk is a gateway serving outdated or incorrect data if it caches a stale version.

A gateway's ability to serve content depends entirely on the persistence of that data on the IPFS network.

• If content is only hosted by a single node that goes offline, it becomes unavailable.
• Pinning services (like Pinata, Infura) are often used by gateways to ensure long-term persistence.
• Gateway downtime itself can make content inaccessible even if it exists on IPFS, highlighting a reliance on the gateway's operational reliability.

Gateway performance impacts reliability. Key mechanisms include:

• Edge Caching: Popular gateways use CDNs to cache frequently requested CIDs, speeding up retrieval but potentially serving stale data.
• Initial Fetch Latency: The first request for unpinned content can be slow as the gateway must locate and retrieve it from the distributed network.
• DDoS Resilience: Public gateways are common targets for DDoS attacks, which can degrade service for all users.

Gateways translate between HTTP and IPFS protocols, each with different security models:

• HTTPS: Provides transport encryption between user and gateway, but not end-to-end to the content source.
• IPFS Protocol: Uses libp2p for peer-to-peer communication. A gateway must securely handle libp2p connections to prevent node compromise.
• Subdomain Gateways: Modern practice uses {cid}.ipfs.example.com format for origin isolation, preventing malicious scripts from one CID affecting another.

This is the core technical function of an IPFS Gateway. It translates standard HTTP(S) requests into IPFS protocol requests and vice-versa. The process involves:

1. Request Parsing: The gateway extracts a CID or IPNS name from the URL path.
2. Network Lookup: It queries the distributed hash table (DHT) to find nodes hosting the content.
3. Content Retrieval: It fetches the content from the IPFS network.
4. HTTP Response: It serves the content (e.g., a webpage, image, JSON file) via HTTP with appropriate headers.

IPFS Gateways differ based on their accessibility and configuration:

• Public Gateway: Openly accessible (e.g., ipfs.io, dweb.link). Operated by third parties, they provide easy access but may have rate limits, latency, and trust considerations.
• Private/Local Gateway: A node you run yourself (localhost:8080). It offers full control, privacy, and direct peer-to-peer connectivity without intermediaries.
• Dedicated/Pinned Gateway: Services like Pinata or Cloudflare offer managed gateways that guarantee fast, reliable access to content you have pinned (permanently stored) on their infrastructure.