Generate synthetic nginx access logs

This sample, generated

The block below is 15 lines of nginx access logs, produced by the real generator at seed 42 — deterministic, so this exact output regenerates anywhere. The live tool re-runs the identical engine on whatever source, seed, line count and anomalies you pick.

Generated nginx access logs

Real on-the-wire nginx access logs — no real users, IPs, or secrets. Copy it into a fixture, feed it to a parser, or seed a SIEM demo.

With an anomaly injected: HTTP 5xx spike

The same source, regenerated with a HTTP 5xx spike injected at 30% intensity. 1 line is tagged and highlighted below — A run of 5xx responses from one client/path — an outage or an app under attack a SOC should page on. It is a documented, detectable pattern your SIEM rules should fire on — build the test data, then prove your detection works.

FAQ

Are these real nginx logs?

No — every line is synthetic. The generator emits the exact on-the-wire nginx combined format (IP, CLF timestamp, request, status, bytes, referer, user agent), but the addresses, paths and agents are all fabricated. Nothing comes from a real server or real users, so the output is safe to paste into a ticket, a fixture, or a public demo.

Can I inject anomalies?

Yes. An HTTP 5xx spike slider flips a contiguous run of responses to 500/502/503/504 pinned to one hammering client — the exact shape a SOC should page on. There are five injectable patterns in all; raise a slider and the affected lines are highlighted and badged so you can confirm your detection rules fire on them.

Is the output deterministic?

Yes. Generation is fully seeded: the same source, line count, seed, EPS, format and anomaly settings always produce byte-identical output. Commit a seed to a test fixture and regenerate the exact same nginx log on any machine, in CI, or a year later.

Generate other log sources

• Apache access logs
• sshd / OpenSSH auth logs
• RFC 3164 (BSD) syslog
• RFC 5424 syslog
• FortiGate firewall logs
• Cisco ASA firewall logs
• Windows Security Event logs
• JSON application logs
• Docker container logs
• Kubernetes (klog) logs
• AWS VPC Flow logs

Open the LogAnvil generator to tune the seed, line count, EPS, format and anomaly sliders — or build a parser with LogForge for a log you already have.