Polymorfa

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Polymorfa vs Kapso

Both are developer platforms for WhatsApp with SDKs, a CLI, MCP and customer onboarding. The difference is route coverage and how you pay: Kapso is official-only and meters messages; Polymorfa adds linked-device numbers and bills per online number-day.

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Choose Kapso if

  • You only need the official Cloud API and never linked-device numbers.
  • You want workflows with an LLM step, hosted Functions and an embeddable inbox in one plan.
  • Your message volume fits inside a plan allowance, starting free at 2,000 messages a month.

Choose Polymorfa if

  • Your customers already run WhatsApp or WhatsApp Business app numbers as linked devices.
  • You send many messages per number and want the platform charge to follow online days, not message count.
  • You need SIP trunks, video calls on linked-device numbers, or idempotent sends.
  • You want to test in CI against simulated numbers instead of a shared real number.
Routes

Linked-device numbers and the Cloud API, one integration.

Kapso's connection guide covers official numbers: a new US number, coexistence with the WhatsApp Business app, or your own SIM. Polymorfa connects those official numbers (in beta) and also existing WhatsApp and WhatsApp Business app numbers as linked devices.

Messages, reactions and webhooks use the same API on both routes. Edits, deletes, groups and channels work on linked-device numbers.

Linked deviceQR or pairing code
Cloud APIOfficial Meta route
One Polymorfa APISame messages, webhooks, SDKs
Your applicationOne integration
Both WhatsApp routes arrive through one contract. Moving a number between routes does not mean rewriting your integration.
Pricing

Pay for online days, not for messages.

Kapso plans include a message allowance: 2,000 on Free, 100,000 on Pro, 1,000,000 on Platform. Polymorfa charges a number for each day it is online, whatever it sends.

Kapso bundles storage, workflows and an inbox into its plans, so compare the whole bill for your workload. Meta's fees apply to Cloud API numbers on both.

One number, one monthIllustrative values
Online days billed
22
Messages metered
0
Polymorfa bills a number for the days it is online. Message volume on that number does not change the platform charge. Meta's own fees still apply to Cloud API numbers.
Calls

Calls in the browser, in server code and on your PBX.

Kapso's SDK places and answers official calls over WebRTC. Polymorfa also connects calls to your PBX over SIP trunks, runs video calls on linked-device numbers, and gives server code the raw audio.

Incoming WhatsApp callcall.received webhook
Polymorfa callsVoice and video, one call object
Browser
Server code
SIP / PBX
Answer in a browser, from server code that reads and writes the audio, or on your own PBX over SIP. The same webhooks follow every call.
Testing

Test in CI without a shared number.

Kapso's sandbox is a shared real number with limits. Polymorfa's test numbers (in beta) are simulated, cost 0 credits, and use the same API your production code calls.

CI run against the simulator
  • delivers a text and receives the ack
  • handles an inbound reply webhook
  • recovers after a forced disconnect
  • rejects an unsigned webhook
No real phone number used
Test against a simulated WhatsApp server in CI, with the same API your production code calls.
Fair comparison

Where Kapso is ahead.

Kapso ships a workflow builder with an LLM agent step, hosted Functions, an embeddable team inbox and an official n8n node. Polymorfa has no inbox app, and its Functions are in private beta.

If you only need the official route and your volume fits a plan allowance, Kapso is a complete choice. Its Free plan includes a number and 2,000 messages a month.

Side by side

Polymorfa and Kapso, feature by feature.

Every row, every product. Hover a feature name for a definition.

Feature
PolymorfaWhatsApp infrastructure API
KapsoOfficial Cloud API platform
Connection routes
YesQR code or pairing code
Not listedOfficial connections only in its docs
BetaMeta Embedded Signup; needs beta access
YesMeta partner
BetaKeep using the WhatsApp Business app
Yes
Both routes behind one API
Sends and reactionsEdits, deletes, groups and channels are linked-device only
Official route only
Pairing code (no camera)
In QuickLink
Not applicable
Hosted onboarding link for your customers
QuickLink
Setup links
Import existing sessions without rescanning
PreviewBaileys sessions; others assisted
Not applicable
Messaging
Media, polls, reactions, edits, deletes
YesEdits and deletes on linked device
Cloud API message types
Group management
Linked device
Waitlist
Channels
Linked device
Not listed
Status posts
Not listed
Not listed
Message templates
YesSubmitted to Meta for review
Yes
Scheduled campaigns
Pro numbers
BroadcastsTemplate messages only
24-hour keys
Not listed
Hosted message history
Beta
Yes
Media storage
Hosted
1 GB to 1 TB by plan
Calls
Incoming call events
11 call events
Accept or reject
Place and answer calls from code
Browser, server, SIP
WebRTC via SDK
Video calls
Linked deviceCloud API calls are one-to-one audio
Not listed
SIP trunk to your PBX
Both directions
Not listed
Browser calling components
React and web componentPrerelease SDK
Not listed
Call history
With quality stats
Call logs
Automation and AI
Visual flow builder
WhatsApp Flows formsNot a chatbot builder
Workflow builder
Hosted serverless functions
Private beta
Yes
MCP server for AI agents
Hosted, 190 tools
Hosted
n8n, Zapier or Make
n8n, Zapier, Make
n8n
Built-in AI replies
Bring your ownConnect any agent over MCP or the API
Agent step in workflows
Developer experience
REST API with OpenAPI spec
OpenAPI 3.1
Yes
Official SDKs
TS · Python · Go · PHP · Rust
TypeScript
Official CLI
Prerelease
Yes
Signed webhooks with retries
HMAC-SHA256Up to 8 attempts over about 41 hours
HMAC-SHA2563 attempts over about 50 seconds
Streaming event feed
SSE, beta
Not listed
Free test environment
Beta test numbers0 credits
Shared test number
BetaSimulated test numbers
Flows emulator only
Embeddable UI components
Call components
Embedded inbox (iframe)
Operations and safety
Number health estimate
0–100, rules-basedProduction linked-device numbers
Health check, quality rating
Typing, pacing and presence controls
Standard and ProEvery setting is off until you turn it on
Not applicable
Per-number proxy
Not offered
Not applicable
Customer accounts for SaaS builders
Customers API
Customers API
Branded onboarding
Branded QuickLink$50 a month add-on
Setup link colors
Team roles and scoped API keys
Roles and scoped keys
4 roles, project keys
Audit log
With export
Not listed
Team inbox app
Shared agent inbox
Not offered
Yes
Built-in CRM or pipeline
Not offered
Contacts and assignment
Deployment and pricing
Managed cloud
Yes
Yes
Self-hosting
Not offered
Open-source inbox only
Source license
Proprietary
Inbox and SDK (MIT)
Pricing model
Per online number-day
Plan with message allowancePlus per-number fees above the plan
Paid entry price
$0.25 per online dayStandard number; +55 numbers cost 15% less
$25 a monthPro: 3 numbers, 100,000 messages
Free tier or trial
1 project, 1 real numberFree team
1 number, 2,000 messages
Region choice
Not selectable
Not listed

Checked against each vendor's public website and documentation on 24 September 2026. “Not listed” means we did not find the capability on those pages. It does not mean the product lacks it. Prices are list prices shown publicly on that date and exclude Meta's fees and taxes unless stated.

Spotted something out of date? Tell us and we will correct it.

Sources

Polymorfa

Kapso

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