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Cloud · head to head

HAProxy vs Thanos

HAProxy logo

HAProxy

Cloud

High-performance TCP and HTTP load balancer

From
Free
Rated
-
Full reviewWebsite
Thanos logo

Thanos

Cloud

Highly available Prometheus with long-term object storage

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: HAProxy configuration syntax is dense and unforgiving, with a steep initial learning curve; Thanos several components — sidecar, store, querier, compactor, ruler — each with its own configuration and failure modes
  • They diverge on capability: HAProxy covers High throughput, Thanos covers Global query.
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which HAProxy and Thanos actually diverge.

Attributes where HAProxy and Thanos differ
AttributeHAProxyThanos
PlatformsLinux, Docker, Kubernetes, Self-hostedKubernetes, Linux, Docker

Identical on both: starting price (Free), pricing model (Open source, no licence fee), free tier (Yes), user rating (Not yet rated), category (Cloud).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in HAProxy

  • High throughput
  • Layer 4 and 7
  • Health checking
  • Rate limiting and ACLs

Only in Thanos

  • Global query
  • Object storage retention
  • Deduplication
  • Downsampling

What people use each for

The jobs each tool is most often brought in to do.

HAProxy

  • Load balancing at traffic levels where proxy efficiency shows up in the hardware billnot Thanos
  • Precise traffic control — rate limits, sticky sessions, complex routing rulesnot Thanos
  • TCP load balancing for databases and non-HTTP servicesnot Thanos

Thanos

  • Querying metrics across many clusters or regions from one placenot HAProxy
  • Retaining metrics for years without local disk growthnot HAProxy
  • Removing the gap that appears when a single Prometheus instance restartsnot HAProxy

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

HAProxy

  • Configuration syntax is dense and unforgiving, with a steep initial learning curve
  • No automatic certificate management, unlike newer servers that treat it as default behaviour
  • The built-in stats page is basic, so real observability needs exporters and dashboards
  • A dedicated load balancer is more machinery than small deployments need

Thanos

  • Several components — sidecar, store, querier, compactor, ruler — each with its own configuration and failure modes
  • The compactor is a common source of operational trouble and must not run twice against the same bucket
  • Query latency over object storage is meaningfully higher than local Prometheus
  • Object storage costs and API request charges become real at high volume

Pricing, plan by plan

HAProxy

Free
  • HAProxyFree
    • Full functionality
    • No usage limits
    • Community support

Thanos

Free
  • ThanosFree
    • Full functionality
    • No usage limits
    • Community support

Which should you pick?

Choose HAProxy if

  • You need high throughput.
  • You want to start without paying.
  • You work on Linux, Docker, Kubernetes, Self-hosted.
  • You also want layer 4 and 7.
HAProxy review

Choose Thanos if

  • You need global query.
  • You want to start without paying.
  • You work on Kubernetes, Linux, Docker.
  • You also want object storage retention.
Thanos review

Questions people ask

Is HAProxy or Thanos better?
Neither clearly leads. HAProxy starts at Free and Thanos at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, HAProxy or Thanos?
HAProxy starts at Free and Thanos at Free.
Does HAProxy or Thanos run on more platforms?
HAProxy runs on Linux, Docker, Kubernetes, Self-hosted. Thanos runs on Kubernetes, Linux, Docker.
Can I use HAProxy for free?
Both have a free tier, so you can try either at no cost before committing.
What is HAProxy best used for?
HAProxy is most often used for load balancing at traffic levels where proxy efficiency shows up in the hardware bill, precise traffic control — rate limits, sticky sessions, complex routing rules, tcp load balancing for databases and non-http services. Of those, load balancing at traffic levels where proxy efficiency shows up in the hardware bill and precise traffic control — rate limits, sticky sessions, complex routing rules are not what Thanos is typically brought in for.
What can HAProxy do that Thanos cannot?
HAProxy covers High throughput, Layer 4 and 7, Health checking, Rate limiting and ACLs. Thanos covers Global query, Object storage retention, Deduplication, Downsampling.

Answered from the vendors’ own pages

HAProxy: Is HAProxy free?

Yes, the community version is open source. HAProxy Technologies sells HAProxy Enterprise separately.

Thanos: Is Thanos free?

Yes, open source and CNCF-incubating. Costs are the object storage it uses.

HAProxy: HAProxy or Nginx?

HAProxy is a specialist load balancer with deeper balancing and health-check features. Nginx also serves static content and is more approachable, which is why it is more common as a general web server.

Thanos: Does Thanos replace Prometheus?

No. It runs alongside existing Prometheus servers, adding global query, deduplication and long-term storage.

HAProxy: Does HAProxy handle TLS certificates automatically?

No. Certificate issuance and renewal are external, unlike Caddy where it is automatic.

Thanos: Thanos or VictoriaMetrics?

Thanos layers onto Prometheus using object storage and is the more established multi-cluster answer. VictoriaMetrics is a separate store aiming at lower resource use and fewer moving parts.

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