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APIs · head to head

Ably vs Basis Theory

Ably logo

Ably

APIs

Realtime data delivery platform for pub/sub messaging at scale

From
Free
Rated
-
Full reviewWebsite
Basis Theory logo

Basis Theory

APIs

Developer tokenisation platform that holds card and sensitive data inside a PCI Level 1 environment you do not operate

From
$995/month
Rated
-
Full reviewWebsite

The short version

  • Only Ably has a free tier, so it costs nothing to try first.
  • Each has a real cost: Ably standard and Pro plans layer usage-based charges for messages, connection minutes, and data transfer on top of the base subscription, adding cost complexity.; Basis Theory the Starter plan is 995 US dollars a month before any volume, which is a real floor for an early stage company and puts the product out of reach of teams tokenising a few thousand records.
  • They diverge on capability: Ably covers Pub/sub messaging, Basis Theory covers Tokenisation API.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Ably and Basis Theory actually diverge.

Attributes where Ably and Basis Theory differ
AttributeAblyBasis Theory
Starting priceFree$995/month
Pricing modelfreemiumPer month by token volume
Free tierYesNo
Platformsweb, ios, android, apiWeb, iOS, Android, Linux

Identical on both: user rating (Not yet rated), category (APIs).

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 Ably

  • Pub/sub messaging
  • Presence
  • Message persistence
  • Multi-protocol support
  • Encryption
  • Datadog integration

Only in Basis Theory

  • Tokenisation API
  • Hosted elements
  • Outbound proxy
  • PCI attestation of compliance
  • Processor portability
  • Reactors
  • Access controls and audit
  • PII and PHI options

What people use each for

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

Ably

  • Building realtime chat or collaborative appsnot Basis Theory
  • Delivering live data feeds like stock prices or sports scoresnot Basis Theory
  • Broadcasting notifications to many concurrent clientsnot Basis Theory
  • Running mission-critical realtime infrastructure with high uptime SLAsnot Basis Theory

Basis Theory

  • A payments company that wants card on file without bringing its own infrastructure into PCI scope and paying for the assessment that followsnot Ably
  • A merchant locked into a processor by that processor vault that wants to hold its own tokens and route to more than one acquirernot Ably
  • A fintech collecting bank account and identity data that needs it isolated from its application database before an enterprise security reviewnot Ably
  • A team that needs to send stored card data to a third party for a one-off integration without that data traversing its own serversnot Ably

Where each one falls short

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

Ably

  • Standard and Pro plans layer usage-based charges for messages, connection minutes, and data transfer on top of the base subscription, adding cost complexity.
  • The jump from Standard ($29/month) to Pro ($399/month) is steep for teams needing more than 10k connections but not full Pro capacity.
  • 24/7 mission-critical support and 99.999% uptime SLAs are reserved for the custom-priced Enterprise tier.

Basis Theory

  • The Starter plan is 995 US dollars a month before any volume, which is a real floor for an early stage company and puts the product out of reach of teams tokenising a few thousand records.
  • Starter is limited to the US region, so a company with European data residency requirements is pushed into a quoted Scale or Enterprise agreement immediately.
  • Log retention on Starter is 24 hours, which is well below what most security teams expect for a system holding cardholder data and forces an upgrade for reasons unrelated to volume.
  • Migrating away means moving card data out of the vault, which requires processor and assessor involvement and is slow, so the portability argument that attracts buyers cuts against them at exit.
  • An attestation of compliance covers the vendor environment, not your assessment; your assessor still decides what is in scope, and buyers occasionally discover their integration pattern pulled systems back into scope anyway.

Pricing, plan by plan

Ably

Free
  • FreeFree
    • 200 concurrent connections
    • 500 messages/second
    • 6M messages/month
  • Standard$29/month
    • 10k concurrent channels
    • 10k concurrent connections
    • 2.5k messages/second
  • Pro$399/month
    • 50k concurrent channels
    • 50k concurrent connections
    • 10k messages/second

Basis Theory

$995/month
  • Starter$995/month
    • 20,000 tokens included
    • Production PCI Level 1 environment
    • US region only
  • Scale$undefined/month
    • Quoted
    • Higher token volumes
    • Additional regions
  • Enterprise$undefined/month
    • Quoted
    • Additional compliance options for PII and PHI
    • Responses for 95 percent of PCI SAQ D

Which should you pick?

Choose Ably if

  • You need pub/sub messaging.
  • You want to start without paying.
  • You work on web, ios, android, api.
  • You also want presence.
Ably review

Choose Basis Theory if

  • You need tokenisation api.
  • You work on Web, iOS, Android, Linux.
  • You also want hosted elements.
Basis Theory review

Questions people ask

Is Ably or Basis Theory better?
Neither clearly leads. Ably starts at Free and Basis Theory at $995/month, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Ably or Basis Theory?
Ably has a free tier; the other does not. Paid plans start at Free for Ably and $995/month for Basis Theory.
Does Ably or Basis Theory run on more platforms?
Ably runs on web, ios, android, api. Basis Theory runs on Web, iOS, Android, Linux.
Can I use Ably for free?
Yes. Ably has a free tier, so you can try it without paying. Basis Theory starts at $995/month.
What is Ably best used for?
Ably is most often used for building realtime chat or collaborative apps, delivering live data feeds like stock prices or sports scores, broadcasting notifications to many concurrent clients, running mission-critical realtime infrastructure with high uptime slas. Of those, building realtime chat or collaborative apps and delivering live data feeds like stock prices or sports scores are not what Basis Theory is typically brought in for.
What can Ably do that Basis Theory cannot?
Ably covers Pub/sub messaging, Presence, Message persistence, Multi-protocol support. Basis Theory covers Tokenisation API, Hosted elements, Outbound proxy, PCI attestation of compliance.

Answered from the vendors’ own pages

Ably: What does Ably cost?

Ably offers a free plan with 200 concurrent connections, a Standard plan at $29/month plus usage, a Pro plan at $399/month plus usage, and custom Enterprise pricing with unlimited channels and connections.

Source
Basis Theory: Does this make us PCI compliant?

It removes cardholder data from your systems and gives you an AOC plus documented responses for most of a SAQ D. Your assessor still determines your scope, and a careless integration can pull systems back in.

Ably: Is there a free plan, and what are its limits?

Yes, the free plan includes 200 concurrent connections, 500 messages per second, and 6 million messages per month with community and best-effort email support.

Source
Basis Theory: What does it cost to start?

995 US dollars a month on Starter, including 20,000 tokens, a production PCI Level 1 environment and US hosting. Higher tiers are quoted.

Ably: How is usage metered?

Beyond plan limits, Ably charges usage-based rates of $2.50 per million messages, $1.00 per million connection minutes, $1.00 per million channel minutes, and $0.25 per GiB of data transfer, with volume discounts available.

Source
Basis Theory: Can we switch payment processors without re-collecting cards?

Yes, that is the main non-compliance reason to buy it. You hold the tokens and detokenise into whichever processor you route to.

Basis Theory: Is data stored outside the United States?

Not on Starter, which is US only. Other regions require a Scale or Enterprise agreement.

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