# Free Solana WebSocket Providers

## 1. Alchemy
- **Endpoint**: `wss://solana-mainnet.g.alchemy.com/v2/YOUR_API_KEY`
- **Free Tier Limits**:
  - 300M Compute Units (CUs) monthly (~12M transactions)
  - 10 concurrent requests per WebSocket connection on free tier
  - 20,000 WebSocket connections per API Key limit
  - 1,000 parallel WebSocket subscriptions per connection
- **Authentication**: API key required (free signup)
- **Pros**:
  - Large monthly CU allocation
  - Professional infrastructure
  - 99.9% uptime SLA
  - Additional features (Smart Wallets, Webhooks)
- **Cons**:
  - Severe concurrent request limit on free tier (only 10)
  - Some users report issues with Solana WebSocket implementation
  - Requires registration

## 2. PublicNode
- **Endpoint**: `wss://solana-rpc.publicnode.com`
- **Limits**: None specified (completely free)
- **Authentication**: None required
- **Pros**: 
  - No registration needed
  - No API keys
  - Privacy-focused
  - Simple to get started
- **Cons**: 
  - No SLA or uptime guarantees
  - May have undocumented rate limits
  - No support

## 2. Helius
- **Endpoint**: `wss://mainnet.helius-rpc.com/?api-key=YOUR_API_KEY`
- **Free Tier Limits**:
  - 1M credits per month
  - 10 requests per second
  - Standard WebSockets included
- **Authentication**: API key required (free signup)
- **Pros**:
  - Reliable infrastructure
  - Community support
  - Additional APIs available (NFT, Token APIs)
  - Clear rate limits
- **Cons**:
  - Limited credits (1M/month)
  - Enhanced WebSockets only on paid tiers
  - Requires registration

## 4. QuickNode
- **Endpoint**: `wss://YOUR_ENDPOINT_NAME.quiknode.pro/YOUR_TOKEN/`
- **Free Tier Limits**:
  - 10M credits per month
  - WebSocket responses cost 50 credits each
  - ~200,000 WebSocket responses per month
- **Authentication**: Endpoint URL with token
- **Billing Model**: Pay per response, not per subscription
- **Pros**:
  - Generous credit allocation
  - Professional infrastructure
  - Good documentation
  - Multiple solutions (WebSockets, Streams, gRPC)
- **Cons**:
  - Credit-based billing for responses
  - Advanced features require paid plans
  - Must track response usage

## 4. Solana Public RPC
- **Endpoint**: `wss://api.mainnet-beta.solana.com`
- **Limits**: Subject to change without notice
- **Authentication**: None
- **Pros**:
  - Official Solana endpoint
  - No registration required
  - Completely free
- **Cons**:
  - NOT for production use
  - Aggressive rate limiting
  - Can block IPs without warning
  - No SLA or reliability guarantees
  - Poor performance under load

## Recommendations

1. **For Development/Testing**: Use PublicNode or Solana Public RPC
2. **For Small Projects**: Helius (1M credits) or PublicNode
3. **For Medium Projects**: Alchemy (300M CUs but with concurrent limit) or QuickNode (10M credits)
4. **For High-Volume HTTP with occasional WebSocket**: Alchemy (best CU allocation)
5. **For WebSocket-Heavy Applications**: Avoid Alchemy free tier due to 10 concurrent request limit

## Important Notes

- WebSocket subscriptions are stateful - you cannot easily switch providers mid-subscription
- Each provider may have slight differences in response format or timing
- Always implement reconnection logic for production applications
- Consider implementing client-side failover rather than load balancing for WebSockets
- Monitor your usage carefully, especially on QuickNode where responses consume credits