Custom CRMs

Connect WhatsApp to an In-House or Custom CRM

If your CRM is something your team built, every integration conversation starts the same way: is there a connector for us? Usually not, and you end up waiting for a vendor roadmap that never quite arrives.

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webhook-handler.js

     app  .  post  (  "/webhooks/whatsyncs"  ,     async     (  req  ,   res  )     =  >     {          if     (  !  verifySignature  (  req  .  rawBody  ,   req  .  get  (  "X-WhatSyncs-Signature"  )  ,   SECRET  )  )     {            return   res  .  sendStatus  (  401  )  ;          }               // Acknowledge fast, then process out of band. WhatSyncs retries on timeout,          // so slow handlers cause duplicate deliveries rather than lost events.        res  .  sendStatus  (  200  )  ;               const   event   =   req  .  body  ;          const   key   =   req  .  get  (  "X-WhatSyncs-Idempotency-Key"  )  ;          if     (  await     seenBefore  (  key  )  )     return  ;               await   queue  .  publish  (  "whatsapp-events"  ,     {   key  ,   event   }  )  ;      }  )  ;

Requirement: An HTTPS endpoint
Schema: Entirely yours
Connector: Not needed
Support: Same platform as everyone else

Your CRM is not on anybody's integration list

In-house systems are common in businesses with unusual processes — property, logistics, healthcare administration, brokerages — and they are usually well-fitted to the business. What they are not is on a vendor's marketplace.

So the WhatsApp integration conversation stalls, or turns into a proposal to replace a system that works because it is the only way to get the channel connected.

Events, not assumptions

WhatSyncs does not assume anything about your data model. You receive a normalized event and decide what it becomes: a row, a document, a queue message, a call to an internal service.

The hard parts are already handled

Building this yourself means owning session management, reconnects, media downloads and deduplication forever. Those are not features of your CRM; they are infrastructure you would be maintaining instead of building product.

How it helps

Events, not assumptions

WhatSyncs does not assume anything about your data model. You receive a normalized event and decide what it becomes: a row, a document, a queue message, a call to an internal service.

You own the mapping No predetermined objects, no required fields, no vendor opinion about your schema.
Any stack PHP, .NET, Node, Python, Go — anything that can accept an HTTPS POST and make one.
Send from the same number Your system replies through the API from the number the customer already knows.

Amira Khan

Contact · Your CRM · Deal: Villa 17

Activity

WhatsApp · Sales

09:41

Hi — is Villa 17 still available for viewing this weekend?
WhatsApp · Sales

09:43

It is. Sending the brochure and floor plan now.
Synced to record

09:43

villa-17-brochure.pdf · 2.4 MB
WhatsApp · Sales

09:52

Voice note · 0:24

In practice

The hard parts are already handled

Deduplicated upstream Reconciliation happens before delivery, so your database does not need to defend against duplicates alone.
Media as a separate event Metadata first, then an authenticated download when your worker is ready.
Health you can act on Connection events go straight into your existing monitoring.

webhook-handler.js

     app  .  post  (  "/webhooks/whatsyncs"  ,     async     (  req  ,   res  )     =  >     {          if     (  !  verifySignature  (  req  .  rawBody  ,   req  .  get  (  "X-WhatSyncs-Signature"  )  ,   SECRET  )  )     {            return   res  .  sendStatus  (  401  )  ;          }               // Acknowledge fast, then process out of band. WhatSyncs retries on timeout,          // so slow handlers cause duplicate deliveries rather than lost events.        res  .  sendStatus  (  200  )  ;               const   event   =   req  .  body  ;          const   key   =   req  .  get  (  "X-WhatSyncs-Idempotency-Key"  )  ;          if     (  await     seenBefore  (  key  )  )     return  ;               await   queue  .  publish  (  "whatsapp-events"  ,     {   key  ,   event   }  )  ;      }  )  ;

Questions this raises

What do I actually need to build?

An HTTPS endpoint that verifies the signature, stores the event with its idempotency key, returns 2xx quickly, and processes asynchronously. Then whatever writing that event into your system requires.

For most teams that is a few days of work, and the WhatsApp-specific portion of it is small.

Can we run this alongside a commercial CRM?

Yes. Nothing stops one integration writing to both an in-house system and a commercial CRM — the event is delivered once and what you do with it is your decision.

Do we get the same features as a bigger customer?

Yes. There is no enterprise-only API. The Free plan includes full API access, webhooks, media sync and monitoring.

FAQ

Frequently asked

See all questions

Can I use my own in-house CRM?

Yes, and it is one of the most common setups. Custom and in-house systems integrate the same way as commercial CRMs: point a webhook endpoint at WhatSyncs to receive events and call the REST API to send messages or pull conversations.

Can developers use the WhatSyncs API?

Yes. WhatSyncs is built API-first: authenticated REST endpoints for messages, conversations, media and connections, plus signed webhooks with retries and idempotency keys so events can be processed safely.

Can I receive incoming messages through webhooks?

Yes. Incoming and outgoing messages, message status updates and connection events are delivered to your endpoint as they happen. Payloads can be signed so your systems can verify that an event originated from WhatSyncs, and failed deliveries are retried.

How does WhatSyncs avoid duplicate messages?

Every message carries a stable identifier, and WhatSyncs reconciles messages seen through real-time events, reconnects and history synchronization against it. Webhook deliveries also carry an idempotency key so a retry does not create a second record in your CRM.

Keep reading

Custom CRM integration Implementation steps. Read more

For developers What the platform handles. Read more

Receiving messages A step-by-step guide. Read more

WhatsApp API Endpoints and authentication. Read more

Your WhatsApp. Your systems. In sync.

Start with up to 3 WhatsApp connections and 1,000 active chats per month. No credit card required.

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app . post ( "/webhooks/whatsyncs" , async ( req , res ) = > { if ( ! verifySignature ( req . rawBody , req . get ( "X-WhatSyncs-Signature" ) , SECRET ) ) { return res . sendStatus ( 401 ) ; } // Acknowledge fast, then process out of band. WhatSyncs retries on timeout, // so slow handlers cause duplicate deliveries rather than lost events. res . sendStatus ( 200 ) ; const event = req . body ; const key = req . get ( "X-WhatSyncs-Idempotency-Key" ) ; if ( await seenBefore ( key ) ) return ; await queue . publish ( "whatsapp-events" , { key , event } ) ; } ) ;

Your CRM is not on anybody's integration list

So the WhatsApp integration conversation stalls, or turns into a proposal to replace a system that works because it is the only way to get the channel connected.

Events, not assumptions

WhatSyncs does not assume anything about your data model. You receive a normalized event and decide what it becomes: a row, a document, a queue message, a call to an internal service.

You own the mapping No predetermined objects, no required fields, no vendor opinion about your schema.

Any stack PHP, .NET, Node, Python, Go — anything that can accept an HTTPS POST and make one.

Send from the same number Your system replies through the API from the number the customer already knows.

The hard parts are already handled

Deduplicated upstream Reconciliation happens before delivery, so your database does not need to defend against duplicates alone.

Media as a separate event Metadata first, then an authenticated download when your worker is ready.

Health you can act on Connection events go straight into your existing monitoring.