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s3-lambda VS Sherlo

Compare s3-lambda VS Sherlo and see what are their differences

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s3-lambda logo s3-lambda

Lambda functions over S3 objects: each, map, reduce, filter

Sherlo logo Sherlo

Visual regression testing for React Native. Compare screenshots on iOS & Android simulators, catch visual regressions before release. Free plan, no credit card.
  • s3-lambda Landing page
    Landing page //
    2022-11-04
  • Sherlo Baseline vs snapshot, side by side
    Baseline vs snapshot, side by side //
    2026-08-05
  • Sherlo Changed pixels highlighted automatically
    Changed pixels highlighted automatically //
    2026-08-05
  • Sherlo Review as a team - report and comment
    Review as a team - report and comment //
    2026-08-05
  • Sherlo Built-in inspector - the code behind any screen
    Built-in inspector - the code behind any screen //
    2026-08-05
  • Sherlo Compare against your Figma design
    Compare against your Figma design //
    2026-08-05

Sherlo is a visual regression testing tool built specifically for React Native. On every build it renders your app on real iOS and Android simulators in the cloud - native rendering, not React Native Web - screenshots every screen, and compares each against the previous version pixel by pixel.

When something changes, the whole team - developers, designers, PMs, and QA - reviews the diffs together in a shared web app and approves or rejects them before release. It catches unintended visual regressions and confirms intended UI changes look exactly as designed, across many devices, screen sizes, themes, and languages.

Sherlo plugs into any CI pipeline and integrates with Storybook, turning your existing stories into an automated visual test suite. The cloud simulators are included from the free plan - no device farm to build, no credit card to start.

Unlike Percy, Applitools, and Chromatic (web-first, multi-platform generalists), Sherlo is the React Native specialist: it tests how your app actually renders on device. Used in production by React Native teams, from fintech to social apps.

s3-lambda

Website
github.com
Pricing URL
-
$ Details
-
Platforms
-
Release Date
-
Edit details

Sherlo

Website
sherlo.io
Pricing URL
Official Sherlo Pricing
$ Details
freemium
Platforms
SaaS Web Cloud CLI
Release Date
2022 January
Startup details
Country
Poland
City
Szczecin
Founder(s)
Dawid Krajewski, Michał Ziółkowski
Employees
1 - 9
Edit details

s3-lambda features and specs

  • Batch processing of S3 objects
    s3-lambda provides a straightforward way to perform batch operations on large numbers of S3 objects, enabling map, filter, and reduce-style processing over entire S3 buckets or prefixes without writing boilerplate code.
  • Familiar functional API
    The library uses a functional programming paradigm with operations like map, filter, and reduce, making it intuitive for JavaScript developers to process S3 objects using patterns they already know.
  • Built-in concurrency control
    s3-lambda handles parallel processing of S3 objects with configurable concurrency, allowing users to control how many operations run simultaneously and avoid overwhelming AWS resources or hitting rate limits.
  • Context-aware operations
    The library provides a context object within each operation that includes useful metadata about the current object being processed, simplifying access to S3 object properties during transformations.
  • Easy integration with Lambda
    Designed to work seamlessly within AWS Lambda functions, making it straightforward to set up event-driven, serverless pipelines for processing large volumes of S3 data without managing infrastructure.

Possible disadvantages of s3-lambda

  • Unmaintained project
    The repository appears to be no longer actively maintained, with limited recent commits and unresolved issues, which raises concerns about long-term reliability, security patches, and compatibility with newer AWS SDK versions.
  • Limited documentation
    The project's documentation is relatively sparse, lacking comprehensive examples, edge case handling guidance, and detailed API references, which can make it challenging for new users to adopt effectively.
  • AWS SDK version dependency
    The library depends on an older version of the AWS SDK for JavaScript, which may conflict with projects using the newer AWS SDK v3 and could miss out on performance improvements and features in updated SDKs.
  • Limited error handling flexibility
    The built-in error handling mechanisms are relatively basic, and handling partial failures or implementing sophisticated retry logic for individual object operations requires additional custom code from the developer.
  • Narrow scope of functionality
    The library is tightly focused on S3 object processing and does not integrate with other AWS services or provide utilities beyond basic map/filter/reduce operations, limiting its usefulness in more complex data pipeline scenarios.

Sherlo features and specs

  • iOS & Android simulators
    Renders your app on real iOS and Android simulators in the cloud - no device farm to manage.
  • Pixel-by-pixel diffs
    Screenshots every screen and compares each against the previous version, flagging changed pixels.
  • Team review app
    Developers, designers, PMs and QA review changes together and approve or reject before release.
  • Storybook integration
    Turns your existing Storybook stories into an automated visual test suite.
  • CI integration
    Runs in CI on every build via the CLI; both platforms in one run.
  • Device/theme/language matrix
    Test across many devices, screen sizes, themes and languages from one config.

Analysis of s3-lambda

Overall verdict

  • s3-lambda is a useful Node.js library for performing operations like map, reduce, and filter directly on S3 objects using Lambda, making it good for developers who need efficient, serverless-based batch processing of S3 data without managing infrastructure. It is well suited for smaller to medium projects but may not be actively maintained for enterprise-scale needs.

Why this product is good

  • Simplifies common S3 batch operations (map, filter, reduce) with a clean, functional API
  • Leverages AWS Lambda for scalable, serverless parallel processing of S3 objects
  • Reduces boilerplate code for iterating over and transforming large numbers of S3 objects
  • Open-source and free to use, allowing customization for specific workflows
  • Integrates well with existing AWS infrastructure and Node.js applications

Recommended for

  • Developers building serverless data pipelines on AWS
  • Teams needing to process or transform large sets of S3 objects without provisioning servers
  • Node.js developers looking for a functional programming approach to S3 operations
  • Projects with batch processing needs that fit within Lambda's execution limits
  • Prototyping or small-to-medium scale ETL tasks involving S3 data

s3-lambda videos

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Sherlo videos

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Visual testing for React Native · Sherlo demo

Category Popularity

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Questions & Answers

As answered by people managing s3-lambda and Sherlo.

What makes your product unique?

Sherlo's answer:

Sherlo is the visual regression testing tool built specifically for React Native. It renders your app on real iOS and Android simulators in the cloud - native rendering, not React Native Web - and diffs every screen pixel by pixel. Web-first tools like Percy, Chromatic, and Applitools can't test how a React Native app actually looks on a device; Sherlo does.

Why should a person choose your product over its competitors?

Sherlo's answer:

Because it's the React Native specialist. Percy, Applitools, and Chromatic are multi-platform generalists that test web-framework Storybook in a browser, not native iOS/Android rendering. Sherlo runs your app on real iOS and Android simulators, covers both platforms in one run, plugs into CI, and includes the cloud simulators from a free plan - no device farm, no credit card.

How would you describe the primary audience of your product?

Sherlo's answer:

React Native teams that ship UI frequently - developers, designers, PMs, and QA who want to catch visual regressions before release. It fits teams already using Storybook and anyone shipping to many devices, themes, and languages who can't check them all by hand.

What's the story behind your product?

Sherlo's answer:

Sherlo was built by React Native developers who kept shipping UI bugs that slipped past functional tests and were painful to catch by hand across devices. Existing tools were web-first and didn't test native mobile rendering - so they built the visual testing tool they wanted for React Native.

Which are the primary technologies used for building your product?

Sherlo's answer:

React Native, TypeScript, an open-source SDK/CLI (github.com/sherlo-io/sherlo), cloud-hosted iOS and Android simulators, and a web app for reviewing diffs. Integrates with Storybook and any CI pipeline.

User comments

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What are some alternatives?

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