Softwr

Cloud · head to head

Kustomize vs Vault

Kustomize logo

Kustomize

Cloud

Template-free customisation of Kubernetes YAML

From
Free
Rated
-
Full reviewWebsite
Vault logo

Vault

Cloud

Manage Secrets and Protect Sensitive Data

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Kustomize no packaging or distribution story, which is exactly what Helm charts provide; Vault vault 1.15.0 and later is licensed under the Business Source License 1.1, not an OSI open source licence, with IBM Corporation as licensor
  • They diverge on capability: Kustomize covers Overlay patching, Vault covers Secrets management.

Where they differ

Only the attributes on which Kustomize and Vault actually diverge.

Attributes where Kustomize and Vault differ
AttributeKustomizeVault
Pricing modelOpen source, no licence feeopen-source
PlatformsKubernetes, Linux, macOS, WindowsLinux, Windows, Mac, Cloud
FoundedUnknown2015

Identical on both: starting price (Free), 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 Kustomize

  • Overlay patching
  • No templating language
  • Built into kubectl
  • Generators

Only in Vault

  • Secrets management
  • Encryption
  • Authentication
  • Authorization
  • Audit logging
  • API access
  • High availability
  • Replication

What people use each for

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

Kustomize

  • Managing dev, staging and production variants of the same manifestsnot Vault
  • Keeping manifests readable and directly applyable rather than templatednot Vault
  • Patching third-party manifests without forking themnot Vault

Vault

  • Centrally storing and rotating secrets, API keys and database credentialsnot Kustomize
  • Issuing short-lived dynamic credentials to applications instead of static passwordsnot Kustomize
  • Encryption as a service and PKI certificate issuancenot Kustomize

Where each one falls short

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

Kustomize

  • No packaging or distribution story, which is exactly what Helm charts provide
  • Deeply nested overlays become hard to follow, and reasoning about the final output requires building it
  • No release lifecycle: nothing tracks what is installed or supports rollback the way Helm does
  • Patch syntax is fiddly for anything beyond simple field replacement

Vault

  • Vault 1.15.0 and later is licensed under the Business Source License 1.1, not an OSI open source licence, with IBM Corporation as licensor
  • The Additional Use Grant forbids offering Vault to third parties on a hosted or embedded basis in a paid product that competes with IBM's paid versions of Vault
  • Each version only converts to MPL 2.0 four years after that version is published, and the Change Date is tracked per version
  • Replication, HSM support, namespaces, performance standby nodes, FIPS builds, control group authorisation, multi-factor authentication, secrets sync and lease count quotas all require a Vault Enterprise licence
  • A Vault Enterprise licence must be applied to the cluster before any Enterprise feature can be used

Pricing, plan by plan

Kustomize

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

Vault

Free
  • Open SourceFree
    • Secrets management
    • Encryption as a service
    • Identity management
  • EnterpriseFree
    • Advanced features
    • Premium support
    • Dedicated updates

Which should you pick?

Choose Kustomize if

  • You need overlay patching.
  • You want to start without paying.
  • You work on Kubernetes, Linux, macOS, Windows.
  • You also want no templating language.
Kustomize review

Choose Vault if

  • You need secrets management.
  • You want to start without paying.
  • You work on Linux, Windows, Mac, Cloud.
  • You also want encryption.
Vault review

Questions people ask

Is Kustomize or Vault better?
Neither clearly leads. Kustomize starts at Free and Vault at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Kustomize or Vault?
Kustomize starts at Free and Vault at Free.
Does Kustomize or Vault run on more platforms?
Kustomize runs on Kubernetes, Linux, macOS, Windows. Vault runs on Linux, Windows, Mac, Cloud.
Can I use Kustomize for free?
Both have a free tier, so you can try either at no cost before committing.
What is Kustomize best used for?
Kustomize is most often used for managing dev, staging and production variants of the same manifests, keeping manifests readable and directly applyable rather than templated, patching third-party manifests without forking them. Of those, managing dev, staging and production variants of the same manifests and keeping manifests readable and directly applyable rather than templated are not what Vault is typically brought in for.
What can Kustomize do that Vault cannot?
Kustomize covers Overlay patching, No templating language, Built into kubectl, Generators. Vault covers Secrets management, Encryption, Authentication, Authorization.

Answered from the vendors’ own pages

Kustomize: Is Kustomize free?

Yes, open source and part of the Kubernetes project.

Vault: Is HashiCorp Vault free to use?

Yes, Vault is available as a free, open-source project. The community version includes secrets management, certificate generation and rotation, encryption services, and credential management. Vault Enterprise is a commercial offering with additional features.

Source
Kustomize: Kustomize or Helm?

Kustomize patches plain YAML and keeps bases readable; Helm templates and packages applications with a release lifecycle. Many teams use both — Helm to install third-party charts, Kustomize to patch them.

Vault: What are the differences between open-source Vault and Vault Enterprise?

Open-source Vault is free and self-hosted. Vault Enterprise includes additional features and commercial support. HashiCorp also offers Vault Dedicated on the HashiCorp Cloud Platform as a fully managed cloud option.

Source
Kustomize: Do I need to install Kustomize?

No. It is built into kubectl, available through kubectl apply -k.

Vault: Can I try HashiCorp Cloud Platform Vault without payment?

Yes, HashiCorp offers a free trial option for HCP Vault Dedicated. New users also receive a $500 credit to use across HashiCorp Cloud Platform services.

Source
Vault: What does Vault manage and protect?

Vault provides identity-based secrets management for users, machines, services, and AI agents. It automates authentication and authorization for access to secrets, passwords, certificates, encryption keys, and other sensitive data across your infrastructure.

Source
Share

Related pages

More on Kustomize

More on Vault

Keep looking

Other head to heads