Celeris vs Ably
An honest side-by-side comparison of Celeris and Ably: performance, pricing, architecture, and when to choose each.
Ably is a capable platform with genuine engineering behind it. This comparison is honest. We will tell you when Ably is the better choice.
TL;DR
Choose Celeris if:
- You need sustained high-throughput pub/sub (we measured 96,114 msg/s on one node)
- Binary messaging (MessagePack, Protobuf) matters to you
- You want predictable, transparent pricing at scale
- You want data in your own infrastructure (BYOD, coming soon)
- You prefer a longer billing cycle (automatic renewal every 10 years)
- You want pure WebSocket transport without SDK lock-in
Choose Ably if:
- You want a built-in Chat SDK or collaborative editing primitives
- You need LiveSync (database-to-frontend sync) out of the box
- Your team is already using Ably and switching cost is high
- You need Ably's specific compliance certifications
Feature comparison
| Feature | Celeris | Ably |
|---|---|---|
| Primary protocol | WebSocket (binary-first) | WebSocket + HTTP fallback |
| Binary messaging (MessagePack, Protobuf) | ✓ | Partial |
| Message ordering | Local or per-origin, and recovery can have gaps | Per-channel |
| Multi-region | US and EU regions via AWS Global Accelerator (130 PoPs) | Global (30+ PoPs) |
| BYOD data export | Coming soon | — |
| Built-in Chat SDK | — | ✓ |
| Collaborative editing primitives | — | ✓ |
| Database sync (LiveSync) | — | ✓ |
| 10-year recurring pricing | ✓ | — |
| Transparent usage-based billing | 3 dimensions | 4+ dimensions |
| Free tier | ✓ | ✓ |
| Raw WebSocket compatible | ✓ | Limited |
| SDK languages | JS/TS, Python, Go and Java built; Rust and Dart specified | See provider documentation |
Payload size and cost
Compare measured encodings of the same data before you project costs. Celeris carries bytes and does not require a JSON conversion. Your application selects and applies the encoding. A binary format can decrease the payload bandwidth, but there is no fixed decrease that applies to every message.
A fair provider comparison must use the same workload, delivery count, encoding, and current plan terms. Payload volume alone is not a bill: connection time, message accounting, included allowances, and other charges can matter. Refer to Celeris pricing for plan information.
Run your own numbers
Enter measured JSON and binary byte sizes and monthly payload deliveries. This calculator compares payload volume, not provider prices. It excludes protocol overhead and does not promise billing savings.
Small payloads add up
Compare your payload volume
Enter the measured sizes for the same data in each format. The defaults use our position update: 48 bytes of JSON and 32 bytes of MessagePack.
Use whole numbers, including zero. Count each recipient as one delivery: one message to 100 clients makes 100 payload deliveries.
- JSON payload volume
- 48 MB
- Binary payload volume
- 32 MB
This binary encoding moves 16 MB less payload data per month.
This result shows the payload volume only. It excludes the protocol overhead, compression, retries, and connection traffic. Lower bandwidth can decrease costs where your infrastructure charges for transferred bytes. This is not a billing estimate or a promise of a lower Celeris bill.
How we measured the example →The honest take
What Ably does well: Ably has years of production history and deep engineering. Its reliability record is strong. It has more features: a Chat SDK, LiveSync, Spaces, and a serverless function layer. If you need those features immediately, Ably is a reasonable choice.
Where Celeris is different: Celeris is a transport layer, not an engagement cloud. We do one thing: high-throughput WebSocket delivery. With a binary-first transport, your application can send encoded bytes without a required JSON conversion. BYOD export, available soon, will put your data in your own infrastructure.
Pricing: The multi-dimensional Ably billing compounds at scale. Celeris has three dimensions, clearly stated, with no per-seat or per-product additions. The 10-year billing option has no Ably equivalent.
The bottom line: If you want an engagement platform with built-in chat SDKs and collaborative editors, Ably is mature. If you want a raw WebSocket transport that stays out of your path, Celeris offers a binary delivery layer. Evaluate the performance and the cost against your own workload.