When evaluating solutions for adding chat functionality to your application, PubNub often appears as an option, but there's a critical distinction to understand. PubNub operates fundamentally differently from popular chat SDK solutions like CometChat, SendBird, and Stream.
At its core, PubNub is a real-time publish-subscribe (pub/sub) infrastructure platform , not a dedicated chat solution. While it can be used to build chat applications, it only provides the foundational building blocks through its pub/sub infrastructure. This means developers must construct most chat features from scratch, investing significant time and resources in development.
While some developers might be drawn to the idea of building chat functionality from the ground up using PubNub's infrastructure, the crucial question remains: Is it economically viable?
In this blog post, we'll analyze PubNub's pricing structure to help you determine whether the additional development effort and resources required are justified compared to more straightforward solutions like CometChat that offer comprehensive chat functionality at competitive pricing.
Pubnub pricing overview
PubNub's pricing model has historically been a point of contention among customers. While other chat providers offer simplified, predictable pricing based on monthly active users (MAU) and deliver built-in features, PubNub's pricing is purely usage-based, focusing on the consumption of its pub-sub infrastructure.
Examples of the transaction types PubNub bills for include
In the context of building a chat application, these transactions can refer to
Replicated transactions: Each message sent or received is considered a replicated transaction.
Edge transactions: Transactions that occur at the network edge, such as presence updates or real-time notifications.
Functions execution: Charges for running custom functions on PubNub's serverless infrastructure.
Data persistence: Fees for storing message history and other data.
While this granular approach offers flexibility, it can make pricing unpredictable. As your application grows, so do the number of transactions, potentially leading to significant cost increases. For example, implementing presence indicators to show whether users are online or offline requires using PubNub's presence API, which generates edge transactions that contribute to your billing.
Similarly, the messages exchanged in your chat application are also counted as replicated transactions, as each connection between the sender/receiver and the pub/sub infrastructure is billed.
This usage-based model makes it challenging to accurately forecast costs, especially for rapidly growing applications. The complex billing structure, with its nuances across different transaction types, can be overwhelming for developers. Additionally, to minimize costs, developers may need to optimize their applications to reduce the number of transactions, which can impact performance and user experience.
Pubnub’s starter plan
PubNub offers a starter plan with an MAU-based pricing model, similar to those of dedicated chat SDKs. However, this plan still comes with certain caveats:
The starter plan only supports up to 1,000 MAUs and 3,000 transactions per MAU.
Exceeding these limits results in overage fees, including:
$0.15 per additional user
$43 per additional 1M transactions
$8 per GB of persistence
$25 per 1M of function executions
While overage fees for MAUs are common across providers, PubNub’s additional transaction-based fees quickly raise costs and reintroduce the unpredictability of its usage-based billing model beyond the limits mentioned in the starter plan.
Although the Starter Plan makes it somewhat easier for newcomers to get started with PubNub, the main drawback still remains.
Hitting transaction limits will quickly inflate costs, requiring constant vigilance to avoid unexpected charges.
Instead of paying for features or users, you’re still indirectly paying for unpredictable usage. MAUs and feature sets are predictable and in your control, but message volume and adoption aren’t, making it counterintuitive to charge users for positive engagement.
PubNub’s commitment to transaction-based billing adds unpredictable expenses that can make scaling prohibitive and stressful.
Complicates development as teams must strategize to reduce transaction volume, undermining the core purpose of a chat solution, which should streamline messaging, not make it more challenging.
For developers seeking reliable chat solutions with predictable costs, CometChat provide easier, feature-rich paths without the financial strain of per-transaction fees.
Pricing comparison: Pubnub vs CometChat
Comparing PubNub with chat-focused solutions like CometChat presents an inherent challenge, as we're essentially comparing a foundation layer with a complete solution. Check the table below to understand the key differences in Pubnub and CometChat’s pricing model.
| Features | Pubnub | CometChat |
|---|---|---|
Pricing model
| Consumption-based. Pricing is based on the number of "transactions," calculated based on API calls generated by your application. Meaning every message, notifications sent or event interaction adds to the monthly cost.
| Simple, MAU-based. Fixed monthly fees based on the number of monthly active users (MAUs).
|
Features
| PubNub provides basic pub/sub messaging infrastructure but lacks built-in chat features, requiring extra time and effort to add core chat functions.
| Ready-to-use chat features including typing indicators, read receipts, media sharing, and real-time notifications.
|
Level of customization
| Offers extensive customization but requires significant developer expertise and additional time to configure and integrate desired features.
| Modular components in CometChat’s UI kits offer ample customization, while SDKs allow deeper adjustments if needed.
|
Cost predictability
| Transactions are subjected to change due to fluctuations in user activity, making costs hard to control and predict.
| Predictable costs as pricing is based on the number of users, not their activity.
|
Available plans
| Single subscription plan. Starting at $98/month, with limits on MAUs and transactions and multiple overage components.
| Multiple plans across different MAU tiers, starting at $239/month. Free Build plan available for testing and MVPs, with support for up to 100 MAUs.
|
Hidden costs and rate limits
| Extra charges apply for storage, function executions, and other usage beyond base limits, leading to unexpected, additional costs.
| No additional costs for essential services such as storage, bandwidth, image processing, translation, and moderation.
|
Concurrency
| PubNub offers unlimited concurrency for applications with large user base. However, this is offset by the additional costs incurred for each individual transaction in your chat app.
| CometChat addresses this need through its Zero Overage Guarantee for enterprise clients, allowing large-scale applications to support concurrent users without incurring additional fees, provided they sign up for CometChat's Enterprise Plan.
|
Cons of Pubnub over CometChat
1. High and unavoidable overage costs
PubNub's pricing model is centered around a single plan with strict limits on Monthly Active Users (MAU) and transactions. Once these limits are exceeded, customers are faced with high overage fees. For example, PubNub charges an additional $0.15 per user above the 1,000 MAU cap, which can quickly add up as your user base grows.
2. Hidden costs and usage limits
PubNub’s pricing model includes transaction limits and usage caps on features like data storage and function executions. As usage grows, these limits can lead to unpredictable costs, forcing customers to pay extra for essential functions that other chat-focused solutions include in their core pricing. These “hidden” fees can complicate billing and make it difficult to predict monthly expenses.
CometChat avoids hidden costs altogether. All essential features, such as message storage, file uploads, and moderation tools, are included within the pricing plan without additional fees. What users see on the CometChat pricing page is what they pay, ensuring straightforward billing and eliminating the worry of usage-based fees as their chat platform scales.
3. Transaction-based pricing requires extra fees for standard chat features
PubNub's consumption-based pricing model means that even basic chat features like presence indicators, notifications, and message delivery are counted as separate transactions, incurring additional fees. This can lead to a scenario where users are paying extra for fundamental functionality that is typically included in the base pricing of dedicated chat solutions like CometChat.
In contrast, CometChat offers these core chat features as part of its standard plans, with no extra charges. This allows customers to focus on building their application without constantly worrying about the cost implications of implementing basic messaging capabilities.
4. Absence of a robust notification engine
PubNub's notification system is limited to basic push notifications and lacks the sophistication and flexibility of CometChat's comprehensive notification engine, which supports:
Push, email, and SMS notifications
Customizable notification settings for private and group chats
Scheduled notifications based on user behavior
Notification templates for consistent, clear alerts
CometChat's advanced notification capabilities enable businesses to provide a more personalized and engaging experience for their users, without incurring extra costs.
5. Lacks advanced moderation capabilities
Compared to CometChat's AI-powered content moderation, rules-based filtering, and automated spam prevention, PubNub's moderation features are relatively basic. PubNub primarily offers simple keyword filtering, leaving businesses to handle more complex content moderation tasks manually.
CometChat's advanced moderation tools, including profanity filters, user behavior monitoring, and group moderation features, help businesses maintain a safe and engaging chat environment for their users. This level of content control and automation is notably absent in PubNub's offering.
In summary, while PubNub may provide the foundational real-time infrastructure, the platform's pricing model, hidden costs, and limited feature set make it a less attractive option compared to CometChat.
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Haris Kumar
Lead Content Strategist , CometChat