In HTTP/1.1 specifications (RFC 7230), there's no defined maximum size for POST requests. The protocol leaves this implementation-dependent, creating important variations across different web servers and frameworks.

Major web servers enforce their own POST size limits:

// Apache configuration example
LimitRequestBody 10000000  // 10MB limit in httpd.conf

// Nginx configuration example
client_max_body_size 20m;  // 20MB limit in nginx.conf

// IIS configuration example
<requestLimits maxAllowedContentLength="30000000" />  // 30MB in web.config

Application frameworks add another layer of constraints:

// Express.js middleware example
app.use(express.json({ limit: '5mb' }));
app.use(express.urlencoded({ limit: '5mb', extended: true }));

// Django settings.py example
DATA_UPLOAD_MAX_MEMORY_SIZE = 2621440  # 2.5MB default
FILE_UPLOAD_MAX_MEMORY_SIZE = 2621440

When dealing with large payloads, consider these approaches:

// Chunked upload implementation example (JavaScript)
async function uploadLargeFile(file) {
  const chunkSize = 5 * 1024 * 1024; // 5MB chunks
  for (let start = 0; start < file.size; start += chunkSize) {
    const chunk = file.slice(start, start + chunkSize);
    await fetch('/upload', {
      method: 'POST',
      body: chunk,
      headers: {
        'Content-Range': bytes ${start}-${start+chunk.size-1}/${file.size}
      }
    });
  }
}

Common error responses and their meanings:

• 413 Payload Too Large: Server-side limit exceeded
• 400 Bad Request: Possible malformed chunked encoding
• 502 Bad Gateway: Upstream server rejected large payload

For performance-critical applications:

// Compression example (Node.js)
const zlib = require('zlib');
app.post('/api/data', (req, res) => {
  const compressed = zlib.gzipSync(JSON.stringify(largeData));
  // Send compressed data with appropriate headers
  res.setHeader('Content-Encoding', 'gzip');
  res.send(compressed);
});

The maximum size of an HTTP POST request is not strictly defined by the HTTP/1.1 protocol specification (RFC 7231). However, practical limitations exist at multiple levels:

// Example Node.js server setting for POST size limit
const express = require('express');
const app = express();

// Set limit to 10MB for JSON payloads
app.use(express.json({ limit: '10mb' }));

// Set limit to 50MB for URL-encoded data
app.use(express.urlencoded({ limit: '50mb', extended: true }));

Web servers typically impose their own POST size limits:

• Apache: LimitRequestBody directive (default 0 = unlimited)
• Nginx: client_max_body_size (default 1MB)
• IIS: maxAllowedContentLength (default 28.6MB)

# Python Flask example
from flask import Flask
app = Flask(__name__)

# Set max content length to 16MB
app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024

For large file uploads, consider:

1. Chunked transfer encoding
2. Streaming uploads
3. Alternative protocols (WebSockets, gRPC)

// Express middleware to handle payload too large
app.use((err, req, res, next) => {
  if (err.type === 'entity.too.large') {
    return res.status(413).json({
      error: 'Payload exceeds size limit'
    });
  }
  next(err);
});