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Amazon MSK vs WarpStream

SEPT 2026 audit

A comparison of Amazon MSK and WarpStream built from values read directly from each provider's own documentation, with the source recorded against every figure.

Updated 11 criteria comparedSources last checked

The short answer

Choose Amazon MSK if…

You are already on AWS and want Kafka inside the same IAM, the same VPC and the same bill. Serverless scales partitions for you and states no maximum retention at all, which nothing else here offers.

Editorial · Palash Bagchi · approved

Choose WarpStream if…

Write-heavy workloads where inter-zone replication is the bill. Data is acknowledged straight into your own object storage, so partitions, reads and storage are not metered at all and only gigabytes written are — $0.01 falling to $0.003 at volume.

Editorial · Palash Bagchi · approved

Consider something else if…

  • Amazon MSK: You want to predict the bill. Five meters run at once and the floor is $0.75 per cluster-hour — about $547 a month before a byte moves. Ingress costs twice egress, the reverse of most of this corpus, and the 2,400-partition ceiling costs about $2.65 a day carrying no traffic.
  • WarpStream: You need an availability commitment at the entry price. The $100 Dev tier carries no uptime SLA whatsoever; the first one is Fundamentals at $500, five times the floor. Lower latency is a Pro-tier feature, which is the honest cost of the object-storage design.

6 sourced criteria separate them — see where, with sources, below.

Visit Amazon MSK documentationVisit WarpStream documentation

No affiliate links, sponsored placements or paid rankings appear on this site. Ordering follows the sourced data and the stated criteria.

01.

At a glance.

CriterionAmazon MSKWarpStream
Pricing
Entry paid plan
$0.75 per cluster-hour on Serverless — about $547 a month for a cluster that has moved no data at all, before partitions, transfer or storage are counted.
$100 a month for the Dev tier, which carries NO uptime SLA, before any per-gibibyte write charge. The first tier with an SLA is Fundamentals at $500.
Pricing modelServerless bills FIVE dimensions simultaneously: $0.75 per cluster-hour, $0.0015 per partition-hour, $0.10 per GB in, $0.05 per GB out and $0.10 per GB-month stored. Provisioned clusters swap the first two for a per-broker hourly rate. Nothing here is a single number.Two lines, not one. A cluster-tier fee — $100 a month for Dev, $500 for Fundamentals, $1,500 for Pro — plus write throughput metered per gibibyte: $0.01/GiB to 50 TiB, falling to $0.003 beyond 6,250 TiB. Reads, partitions and storage are not billed; data sits in your own object storage.
Storage
Storage price$0.10 per GB-month on Serverless.Not charged separately. Data is persisted directly to your own object storage, so durability is the object store's bill rather than WarpStream's.
Queues
Message retentionUnlimited. Serverless states no maximum retention duration, where WarpStream's published configuration is seven days.7 days on the configuration the pricing calculator shows.
Streaming
Throughput ceiling200 Mbps ingress and 400 Mbps egress per Serverless cluster, throttled rather than refused. That is 25 MB/s in — a quarter of what Redpanda Serverless states, once the units are read.The calculator runs from 1 MiB/s to 5 GiB/s of uncompressed write throughput, and the rate falls as the tier rises rather than the ceiling being fixed.
Partition limit
2,400 partition leaders per Serverless cluster for non-compacted topics, and 120 for compacted ones. Partitions are metered as well as capped — $0.0015 per partition-hour, so 2,400 of them cost about $2.65 a day carrying no traffic.
4,096 on Dev, 16,384 on Fundamentals, 50,000 on Pro and 200,000+ on Enterprise. Partitions are capped by tier and not billed.

Only criteria both providers publish appear here; a tinted cell marks a real difference. Criteria only one of them documents are listed below, and an absence there means we found no source — not that the feature is missing. How we source this.

The small bar above a value is inetGeek's own lean toward that side — computed from the same facts shown, never a number the provider published. See the picker below "The short answer" to weigh only the criteria you care about.

02.

Where they differ.

Entry paid plan

Amazon MSK
$0.75 per cluster-hour on Serverless — about $547 a month for a cluster that has moved no data at all, before partitions, transfer or storage are counted.
WarpStream
$100 a month for the Dev tier, which carries NO uptime SLA, before any per-gibibyte write charge. The first tier with an SLA is Fundamentals at $500.
Sources (2) →

Pricing model

Amazon MSK
Serverless bills FIVE dimensions simultaneously: $0.75 per cluster-hour, $0.0015 per partition-hour, $0.10 per GB in, $0.05 per GB out and $0.10 per GB-month stored. Provisioned clusters swap the first two for a per-broker hourly rate. Nothing here is a single number.
WarpStream
Two lines, not one. A cluster-tier fee — $100 a month for Dev, $500 for Fundamentals, $1,500 for Pro — plus write throughput metered per gibibyte: $0.01/GiB to 50 TiB, falling to $0.003 beyond 6,250 TiB. Reads, partitions and storage are not billed; data sits in your own object storage.
Sources (2) →
  • AWS Price List — Amazon MSK, US East (N. Virginia) ↗

    “$0.75 per cluster-hour for serverless cluster in US East (N. Virginia) [...] $0.0015 per partition-hour for serverless cluster in US East (N. Virginia) [...] $0.10 per GB data in for serverless cluster in US East (N. Virginia)”

    Read 2026-09-16 · official pricing

  • WarpStream Pricing ↗

    “uptime sla none 99.9% 99.99% 99.999%* cluster pricing $100/m $500/m $1500/m contact [...] write throughput tiers 50 TiB $0.01/GiB 250 TiB $0.0075/GiB 1250 TiB $0.0055/GiB 6250 TiB $0.004/GiB remainder $0.003/GiB”

    Read 2026-09-16 · official pricing

Storage price

Amazon MSK
$0.10 per GB-month on Serverless.
WarpStream
Not charged separately. Data is persisted directly to your own object storage, so durability is the object store's bill rather than WarpStream's.
Sources (2) →
  • AWS Price List — Amazon MSK, US East (N. Virginia) ↗

    “$0.10 per GB-Mo for serverless cluster storage in US East (N. Virginia)”

    Read 2026-09-16 · official pricing

  • WarpStream Pricing ↗

    “data is durably persisted to object storage before warpstream provides an acknowledgement to the producer. once data is written to object storage, replication is handled by the object store.”

    Read 2026-09-16 · official pricing

Throughput ceiling

Amazon MSK
200 Mbps ingress and 400 Mbps egress per Serverless cluster, throttled rather than refused. That is 25 MB/s in — a quarter of what Redpanda Serverless states, once the units are read.
WarpStream
The calculator runs from 1 MiB/s to 5 GiB/s of uncompressed write throughput, and the rate falls as the tier rises rather than the ceiling being fixed.
Sources (2) →

Partition limit

Amazon MSK

2,400 partition leaders per Serverless cluster for non-compacted topics, and 120 for compacted ones. Partitions are metered as well as capped — $0.0015 per partition-hour, so 2,400 of them cost about $2.65 a day carrying no traffic.

WarpStream

4,096 on Dev, 16,384 on Fundamentals, 50,000 on Pro and 200,000+ on Enterprise. Partitions are capped by tier and not billed.

Sources (2) →

Message retention

Amazon MSK
Unlimited. Serverless states no maximum retention duration, where WarpStream's published configuration is seven days.
WarpStream
7 days on the configuration the pricing calculator shows.
Sources (2) →

When these numbers change, hear about it. Sources are re-checked monthly; a repricing goes out as a short note.

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03.

Documented by only one.

These criteria are published by one provider and not the other. An absence here means we have not found a source, not that the feature is missing.

Kind of free offerWarpStream: Free credit
Credit card to startWarpStream: No
Egress over allowanceAmazon MSK: $0.05 per GB out and $0.10 per GB in on Serverless. Ingress costs twice egress here, which is the reverse of most of this site's corpus.
Uptime SLAWarpStream: None at all on the $100 Dev tier. 99.9% on Fundamentals, 99.99% on Pro, and 99.999% on Enterprise only with multi-region clusters — 99.99% without.
Maximum message sizeAmazon MSK: 8 MiB on Serverless. A larger message fails outright with INVALID_REQUEST rather than being throttled.
04.

Questions this comparison answers.

Entry paid plan: Amazon MSK or WarpStream?

Amazon MSK: $0.75 per cluster-hour on Serverless — about $547 a month for a cluster that has moved no data at all, before partitions, transfer or storage are counted.

WarpStream: $100 a month for the Dev tier, which carries NO uptime SLA, before any per-gibibyte write charge. The first tier with an SLA is Fundamentals at $500.

Should I choose Amazon MSK or WarpStream?

Pick Amazon MSK if You are already on AWS and want Kafka inside the same IAM, the same VPC and the same bill. Serverless scales partitions for you and states no maximum retention at all, which nothing else here offers.

Pick WarpStream if Write-heavy workloads where inter-zone replication is the bill. Data is acknowledged straight into your own object storage, so partitions, reads and storage are not metered at all and only gigabytes written are — $0.01 falling to $0.003 at volume.

Provider pages

Amazon MSKManaged Kafka on AWS, whose serverless tier meters five separate dimensions at once — cluster-hours, partition-hours, data in, data out and storage.WarpStreamA Kafka-compatible service that writes straight to object storage, billed on a single meter — the gigabytes you write — with no inter-zone replication to pay for.

Related comparisons

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Every page here is sourced and dated.