ipfs-smart-gateway

Smart selector and latency tester for IPFS HTTP gateways (vanilla JS, no dependencies).

Checks gateway availability and performance by fetching only the first byte of a CID (using HTTP Range requests) and aborting stalled requests early—making latency testing extremely fast and bandwidth-efficient.

Sorts gateways by latency, supports fallback and custom lists, works in any browser or framework.

Live Demo

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🚀 Features

• Sorts public and custom IPFS gateways by latency
• Automatically picks the best/fastest gateway for a given CID
• Fallback strategy: tries all, picks fastest, randomizes if needed
• Retry logic for failed scans (NEW in v1.3.0)
• User can add and remove their own gateways (persisted in localStorage)
• All gateway lists can be configured at runtime
• Works in plain HTML, Vue, React, Svelte, or any JS app
• Low-level per-gateway check (measureGateway)
• Gateway URL normalization utility (normalizeGatewayUrl)
• No external dependencies

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📦 Installation

npm install ipfs-smart-gateway

Or use via CDN:

<script src="https://unpkg.com/ipfs-smart-gateway/dist/ipfs-smart-gateway.umd.js"></script>

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🧑‍💻 Usage (ESM)

import * as ipfsGateway from 'ipfs-smart-gateway';

ipfsGateway.configure({
  stopOnFirstSuccess: true,
  persistStorage: true,
  timeout: 5000
});

// Overwrite default gateway list
ipfsGateway.setDefaultGateways([
  'https://custom.ipfs.net/ipfs/',
  'https://another.io/ipfs/'
]);

// Add user gateways
ipfsGateway.setUserGateways([
  'https://my-gw.example.com/ipfs/'
]);

// Remove user gateways
ipfsGateway.removeUserGateways([
  'https://my-gw.example.com/ipfs/'
]);

// Run latency checks with retry (NEW in v1.3.0)
const gateways = await ipfsGateway.checkGateways({
  cid: 'Qm...YourCID...',
  retry: 2,           // retry up to 2 times if no gateways respond
  retryDelay: 1500,   // wait 1500 ms between retries
  onStart:   () => console.log('Starting checks...'),
  onSuccess: g  => console.log('✅', g.url, g.time, 'ms'),
  onFail:    g  => console.log('❌', g.url)
});

console.log('Sorted gateways:', gateways);

// Fastest gateway
const picked = ipfsGateway.getPickedGateway();
console.log('Fastest gateway:', picked);

// Fetch content
const text = await ipfsGateway.fetchFromPicked('Qm...YourCID...');
const json = await ipfsGateway.fetchFromPicked('Qm...JsonCID', 'json');

// Normalize any user-supplied URL
const clean = ipfsGateway.normalizeGatewayUrl('ipfs.io/ipfs/');
console.log('Normalized:', clean); // → https://ipfs.io

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🌐 Usage in HTML (UMD)

<script src="https://unpkg.com/ipfs-smart-gateway/dist/ipfs-smart-gateway.umd.js"></script>
<script>
  const cid = 'QmYourCID';
  ipfsSmartGateway.checkGateways({ cid })
    .then(() => {
      const best = ipfsSmartGateway.getPickedGateway();
      console.log('Best gateway:', best);
      return ipfsSmartGateway.fetchFromPicked(cid);
    })
    .then(content => console.log('Content:', content));
</script>

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⚙️ Configuration

ipfsGateway.configure({
  stopOnFirstSuccess: true, // Stop on first working gateway (faster, less traffic)
  persistStorage: false,    // Don't save anything in localStorage (session only)
  timeout: 5000             // Timeout in ms per gateway probe (default: 3000)
});

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📄 API

Gateway Management

• setDefaultGateways(array)
  Overwrite the built-in default gateway list.

• getDefaultGateways()
  Retrieve the current default gateways.

• setUserGateways(array)
  Persist a list of user-defined gateways (max 15).

• getUserGateways()
  Retrieve the current list of user gateways.

• removeUserGateways(array)
  Remove specified gateways from the user list.

• getAllGateways()
  Returns combined default + user gateways.

Gateway Status and Selection

• checkGateways({ cid, retry, retryDelay, onStart, onSuccess, onFail })
  Perform parallel latency and availability checks for the given CID.

  Parameters

  • cid (string): IPFS CID to test.
  • retry (number, optional): Number of retry attempts if no gateways respond. Default: 0.
  • retryDelay (number, optional): Delay in milliseconds between retries. Default: 1000.
  • onStart (function, optional): Callback before any checks.
  • onSuccess (function, optional): Callback for each successful gateway.
  • onFail (function, optional): Callback for each failed gateway.

  Returns
  An array of available gateways sorted by latency.

• measureGateway(url, cid, timeout?)
  Test a single gateway for the given CID and measure response time.

  Parameters

  • url (string): The gateway URL (with or without protocol, /ipfs/ is not required).
  • cid (string): IPFS CID to test.
  • timeout (number, optional): Timeout in ms for this check (default: global timeout).

  Returns
  Milliseconds to respond (number), or null if not available.

  Example

  const ms = await ipfsGateway.measureGateway('https://ipfs.io', 'QmYourCID');
  if (ms !== null) {
    console.log('Gateway is available! Latency:', ms, 'ms');
  } else {
    console.log('Gateway is not available for this CID');
  }

• getSortedGateways()
  Returns gateways sorted by measured latency (fastest first).

• getPickedGateway()
  Returns the fastest gateway URL, or null if none.

• setPickedGateway(url)
  Manually set the picked gateway.

• loadUserGatewaysFromCache()
  Load user gateways from localStorage.

• loadPickedGatewayFromCache()
  Load the last picked gateway from localStorage.

Fetching Content

• fetchFromPicked(cid, format = 'text')
  Fetches from the currently picked gateway.
  format may be 'text', 'json', or 'blob'.

• fetchWithFallback(cid, format = 'text')
  Attempts fetch in order of latency, then random fallback gateways.

Utilities

• normalizeGatewayUrl(raw)
  Normalize / clean up any gateway URL.
  • Adds https:// if the scheme is missing.
  • Removes trailing /ipfs or /ipfs/.
  • Trims extra slashes.
    Returns the normalized URL string.

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📋 Examples

Basic: Check and pick fastest gateway

await ipfsSmartGateway.checkGateways({ cid: 'QmYourCID' });
const sorted = ipfsSmartGateway.getSortedGateways();
console.log('Sorted by latency:', sorted);
const picked = ipfsSmartGateway.getPickedGateway();
const text = await ipfsSmartGateway.fetchFromPicked('QmYourCID');

Test a single gateway

const ms = await ipfsSmartGateway.measureGateway('https://ipfs.io', 'QmYourCID');
if (ms !== null) {
  console.log('Gateway is available! Latency:', ms, 'ms');
} else {
  console.log('Gateway is not available for this CID');
}

Add user gateway and test

ipfsSmartGateway.setUserGateways(['https://my-gw.example.com/ipfs/']);
await ipfsSmartGateway.checkGateways({ cid: 'QmYourCID' });

Remove user gateways

ipfsSmartGateway.removeUserGateways([
  'https://my-gw.example-1.com/ipfs/',
  'https://my-gw.example-2.com/ipfs/'
]);

Fetch as JSON or Blob

const data = await ipfsSmartGateway.fetchFromPicked('QmYourJson', 'json');
const blob = await ipfsSmartGateway.fetchFromPicked('QmFile', 'blob');

Retry if no gateways are found immediately

const gateways = await ipfsSmartGateway.checkGateways({
  cid: 'QmYourCID',
  retry: 1,
  retryDelay: 2000
});
console.log('Available gateways after retry:', gateways);

Listen to gateway check events

await ipfsSmartGateway.checkGateways({
  cid: 'QmTest',
  onStart:   () => console.log('Started...'),
  onSuccess: g  => console.log('✅', g.url, g.time),
  onFail:    g  => console.log('❌', g.url)
});

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🔒 Storage Keys Used

If storage is enabled, the following keys are used in localStorage:

• ipfs-smart-gateway:user-gateways
• ipfs-smart-gateway:picked

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📝 License

MIT

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Note: Some of this documentation and initial scaffolding was generated in collaboration with AI (OpenAI’s ChatGPT).