Stop grepping
through chaos.

Wide events and structured errors for TypeScript. One log per request, full context, errors that explain why and how to fix.

Get Started GitHub

FrontendNuxt / Next.js

API ServerNitro / Express

request logs

live

▍

WorkersBackground jobs

DatabaseQueries & events

? What failed?

? Why?

? Which route?

? How to fix?

? How many affected?

Simple API

Three lines of code.
Full observability.

checkout.post.ts

export default defineEventHandler(async (event) => {
  const log = useLogger(event)

  log.set({ user: { id: user.id, plan: user.plan } })
  log.set({ cart: { items: 3, total: 9999 } })

  return { success: true }
})

outputINFO

INFOPOST/api/checkout(234ms)

user: { id: 1842, plan: "pro" }

cart: { items: 3, total: 9999 }

status: 200

requestId: "req_8f2k..."

✓ One log with full context

Structured Errors

Errors that explain why.

Root cause Fix suggestion AI-parseable

payment.post.ts

throw createError({
  message: 'Payment failed',
  status: 402,
  why: 'Card declined by issuer',
  fix: 'Try a different card',
})

outputERROR

ERRORPOST/api/payment402

message: "Payment failed"

why: "Card declined by issuer"

fix: "Try a different card"

✓ Actionable error messages

Drain Pipeline

Send everywhere.

Batched writes, automatic retries with backoff, and fan-out to multiple destinations. Your logs flow through a pipeline that never blocks your response.

Batching Retry & backoff Fan-out

Non-blocking

Pipeline runs in the background. Your response ships immediately.

Guaranteed delivery

Exponential backoff with jitter ensures logs reach every destination.

Bring your own drain

Write a simple function to send logs anywhere.

evlog-drain.ts

import { createDrainPipeline } from 'evlog/pipeline'
import { createAxiomDrain } from 'evlog/axiom'
import { createSentryDrain } from 'evlog/sentry'

const pipeline = createDrainPipeline({
  drains: [
    createAxiomDrain(),
    createSentryDrain(),
  ],
  batchSize: 50,
  flushInterval: 5000,
})

evlog

BATCH · RETRY · FANOUT

Axiom

OTLP

Sentry

PostHog

Better Stack

+ Custom drains

Frameworks

Your stack. Covered.

One module for Nuxt. First-class Next.js support. Standalone API for everything else.

server/api/checkout.post.ts

export default defineEventHandler(async (event) => {
  const log = useLogger(event)
  const { cartId } = await readBody(event)

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  if (!charge.success) {
    throw createError({
      status: 402,
      message: 'Payment failed',
      why: charge.decline_reason,
      fix: 'Try a different payment method',
    })
  }

  return { orderId: charge.id }
})

app/api/checkout/route.ts

import { withEvlog, useLogger } from '@/lib/evlog'

export const POST = withEvlog(async (req) => {
  const log = useLogger()
  const { cartId } = await req.json()

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  if (!charge.success) {
    throw createError({
      status: 402,
      message: 'Payment failed',
      why: charge.decline_reason,
      fix: 'Try a different payment method',
    })
  }

  return Response.json({ orderId: charge.id })
})

src/checkout.ts

import { createRequestLogger } from 'evlog'

app.post('/checkout', async (c) => {
  const log = createRequestLogger({ method: 'POST', path: '/checkout' })
  const { cartId } = await c.req.json()

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  log.emit()
  return c.json({ orderId: charge.id })
})

src/worker.ts

import { initLogger, createRequestLogger } from 'evlog'

initLogger({ service: 'checkout-worker' })

export default {
  async fetch(request, env) {
    const log = createRequestLogger({
      method: request.method,
      path: new URL(request.url).pathname,
    })

    const { cartId } = await request.json()
    const cart = await env.DB.findCart(cartId)
    log.set({ cart: { items: cart.items.length, total: cart.total } })

    log.emit()
    return Response.json({ orderId: cart.id })
  },
}

scripts/migrate-users.ts

import { initLogger, createRequestLogger } from 'evlog'

initLogger({ service: 'migrate' })

const log = createRequestLogger({ task: 'user-migration' })

const users = await db.query('SELECT * FROM legacy_users')
log.set({ found: users.length })

for (const user of users) {
  await newDb.upsert({ id: user.id, email: user.email, plan: user.plan })
}

log.set({ migrated: users.length, status: 'complete' })
log.emit()

Better logging
by tonight.

Wide events, structured errors, dead simple setup.
Set up evlog in 10 minutes. Your future self will thank you.

Get Started View on GitHub

Stop greppingthrough chaos.

Stop greppingthrough chaos.

Three lines of code.Full observability.

Three lines of code.Full observability.

Errors that explain why.

Errors that explain why.

Send everywhere.

Send everywhere.

Your stack. Covered.

Your stack. Covered.

Better loggingby tonight.

Stop grepping
through chaos.

Stop grepping
through chaos.

Three lines of code.
Full observability.

Three lines of code.
Full observability.

Better logging
by tonight.