Api Response Optimization

Solid fundamentals for making your API responses lighter and faster. You get sparse fieldsets so clients can request only the fields they need, ETag-based caching to avoid sending unchanged data, and compression middleware setup. The performance targets are ambitious but realistic: sub-100ms responses, payloads under 50KB, and significantly reduced CPU usage. The checklist covers the usual suspects like pagination and N+1 prevention. Nothing groundbreaking here, just the standard optimizations you should be doing anyway but probably aren't. Good reference if you're debugging slow endpoints or getting complaints about mobile data usage.

skills.sh installs: 434
GitHub stars: 248
last updated: Aug 21, 2026

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Install

$ npx -y skills add secondsky/claude-skills --skill api-response-optimization --agent claude-code

Installs into .claude/skills of the current project.

Files

API Response Optimization

Reduce payload sizes, implement caching, and enable compression for faster APIs.

Sparse Fieldsets

// Allow clients to select fields: GET /users?fields=id,name,email
app.get('/users', async (req, res) => {
  const fields = req.query.fields?.split(',') || null;
  const users = await User.find({}, fields?.join(' '));
  res.json(users);
});

HTTP Caching Headers

app.get('/products/:id', async (req, res) => {
  const product = await Product.findById(req.params.id);
  const etag = crypto.createHash('md5').update(JSON.stringify(product)).digest('hex');

  if (req.headers['if-none-match'] === etag) {
    return res.status(304).end();
  }

  res.set({
    'Cache-Control': 'public, max-age=3600',
    'ETag': etag
  });
  res.json(product);
});

Response Compression

const compression = require('compression');

app.use(compression({
  filter: (req, res) => {
    if (req.headers['x-no-compression']) return false;
    return compression.filter(req, res);
  },
  level: 6  // Balance between speed and compression
}));