Explore the code Modules you did not write
Start from an existing package for the protocol instead of decoding it again.
Decoded data
Get the swap.
Not the log.
Transactions arrive as the entities your product already talks about, instead of raw events you decode yourself.
- Business entities
- Composable modules
- Reusable packages
- Open source
Ethereum → Firehose → Substreams → PostgreSQL
Interactive illustration
StreamingFast
ecosystem
01 Decoded data
Looks familiar?
Every new contract means a new decoder, written by the person who has the least time.
A proxy was upgraded, the decoder stopped matching, nothing errored, and the chart went flat.
The event decodes correctly and the balance is still wrong.
Want to see your own contracts decoded?
Get an API key
RUST → WEBASSEMBLYDecoding is a layer, not a step.
Turning logs into entities is not a one-off script. It is a layer you version, test and keep correct as contracts change. Substreams packages are that layer, written once and reused: you start from a module that already decodes what you need, and spend your time on the rules that are specific to your product.
Read the guideFilterMapAggregateDeliver
▧ substreams.yamlPACKAGE STRUCTURE
01 specVersion: v0.1.0
02 package:
03 name: token_transfers
04 version: v0.1.0
05
06 modules:
07 - name: map_transfers
08 kind: map
09 inputs:
10 - source: sf.ethereum.type.v2.Block
11 output:
12 type: proto:transfers.Transfers Illustrative excerpt Build a complete package ↗
What you get
Composability
Modules feed modules. The output of one is the input of the next.
Your entities, not ours
Map decoded events onto a swap, a position, a holder, whatever your product calls it.
Open source
You can read the decoding logic you depend on.
One output, many destinations
The same stream lands in a database, a file or your own consumer.
02 Decoded data
How it works
FROM HISTORY TO THE CHAIN HEAD
Historical blocksNew blocks
TRANSACTIONS
TRACES & LOGS
STATE CHANGES
Rich block data. One continuous stream.
Pick a module
Find the package that already handles the protocol you care about.
Model your entities
Write only the rules that are yours.
Stream the result
Send it where you consume it, continuously rather than on a schedule.
Want to see your own contracts decoded?
Get an API key03 Decoded data
What you stop owning
[01]
A decoder per contract, and the day a proxy upgrade breaks it
[02]
A test suite for other people's ABIs
[03]
The gap between a decoded event and a correct balance
Decoded data
Decode your protocol, not an example.
Read the guide ↗Turn transactions into reliable data
Separate decoding from business logic, preserve event order and make every derived value traceable.