MarsCode
MarsCode is an AI coding assistant from ByteDance's Singapore entity, available as a plugin for Visual Studio Code and JetBrains IDEs and as a browser workspace. It completes, generates, explains and fixes code in over 100 languages.
What is MarsCode?
MarsCode is an AI-assisted development tool published by SPRING (SG) PTE. LTD., a Singapore-registered company in the ByteDance group. Its homepage promises to help you code and innovate faster with AI, and the product comes in two shapes: an extension that drops into the editor you already use, and a development environment that runs in the browser.
The assistant is the core. It completes code as you type, suggesting either a single line or an entire function, and turns a comment into a working snippet. It generates code from natural-language instructions, explains unfamiliar project code so that newcomers become productive faster, answers technical questions in a dedicated panel, and identifies defects with a one-click fix. The extension page adds unit-test generation for a selected function, documentation generation for a whole function or line by line, and a Builder Mode marked as new, which breaks a requirement down on its own and works through multi-step coding tasks.
A second strand covers plugin development and deployment: writing code without worrying about the schema or the openapi.json file, generating test data and exercising an API in an environment identical to production, auto-provisioning key-value and file storage, and one-click elastic deployment that also exposes an access API. A third strand is the cloud workspace advertised on the homepage - no download, no configuration, a project created in seconds from a template or imported from a Git repository, with multi-region, multi-cluster deployment.
The plugin installs into Visual Studio Code and JetBrains IDEs and claims support for more than 100 languages, with particular strength in Python, Go, JavaScript, TypeScript, C++, Java, Kotlin, C and Rust. An account is required and can be opened through Google or GitHub. Access is advertised as free, and no price list appears anywhere on the site.
One caveat frames the rest: the product is moving to the Trae brand. Every page title reads Trae, the extension page is titled Trae - Plugin, docs.marscode.com redirects to docs.trae.ai, and the workbench now points visitors towards the Trae desktop IDE.
What it does
- Complete code line by line or a whole function while you type
- Generate code from a comment or a plain-language instruction
- Explain an existing project's code to speed up onboarding
- Detect defects and apply a suggested fix in a single click
- Generate unit tests for a selected function to raise coverage
- Generate documentation for a whole function or line by line
- Break a requirement down and run multi-step coding tasks autonomously
When to use MarsCode / When not to
A quick filter to help you decide if MarsCode is the right fit.
When to use MarsCode
- Developers who want AI assistance inside the editor they already use, rather than switching to a new IDE
- Engineers joining an unfamiliar codebase, who need existing project code explained before they can be productive
- Teams trying to lift unit-test coverage without writing every test by hand
- Polyglot developers moving between Python, Go, JavaScript, TypeScript, C++, Java, Kotlin, C and Rust
- Individual developers, students and small teams with no tooling budget, since access is advertised as free
When not to use MarsCode
- Organisations that must keep their code out of model training, since no opt-out mechanism is documented
- Buyers who need a signed data processing agreement, a published subprocessor list or a SOC 2 or ISO 27001 certificate
- Teams bound by a European data-residency requirement, as hosting is declared in the United States and Singapore only
- Anyone under 18, whom the general age-limit clause of the terms of service excludes outright
- Procurement teams that need a published, predictable price list before they can commit
How to use MarsCode
A typical end-to-end flow, from setup to results.
- Decide how you want to work: as a plugin inside your own editor, or in the browser-based environment advertised on the homepage
- Create an account, or sign in with an existing Google or GitHub account
- For Visual Studio Code, open the Marketplace and search for Trae, or use the one-click install link the site exposes
- Install the extension, then restart the extensions or restart Visual Studio Code entirely
- Sign in from the plugin panel in the left sidebar to unlock AI-assisted coding
- For a JetBrains IDE, go to the JetBrains Marketplace page for the plugin and install it from there
- Fall back on the manual installation guide in the documentation if the marketplace route fails
- Open a project and start typing to get inline completions, or write a comment and let the assistant produce the code
- Select a function to generate its unit tests or its documentation, and use the question-and-answer panel for technical queries
- For the cloud route, create a project from a template or import a Git repository, with nothing to install locally
Pros & Cons
Pros
- Advertised as free to use, with no tier to arbitrate and no published price to budget for
- Installs into Visual Studio Code and JetBrains IDEs, so no change of editor is imposed
- Covers the whole loop around code: completion, generation, explanation, fixing, testing and documentation
- More than 100 languages claimed, with an explicit list of those handled best
- Actively maintained: the JetBrains listing records over 3.5 million downloads and a release dated 4 August 2026
- Backed by a substantial publisher, SPRING (SG) PTE. LTD. of the ByteDance group
- Detailed privacy policy with a legal-basis table and two named GDPR representatives
Cons
- No price list at all: the terms reserve "fees or charges (as applicable)" without publishing any scale
- User content feeds model training and no opt-out mechanism is documented
- The privacy policy declares the collection of keystroke patterns or rhythms
- No data processing agreement, no subprocessor list and no SOC 2 or ISO 27001 certificate published
- Data hosted in the United States and Singapore only, with no European residency option
- Very broad licence granted to the publisher and its partners: perpetual, worldwide, transferable and sublicensable
- Brand and scope in flux: pages are titled Trae, documentation redirects to docs.trae.ai, and the cloud environment advertised on the homepage was not reachable from the workbench
Pricing & Plans
A free plan is available: the homepage invites visitors to start for free and no paid tier is published. There is no pricing page on the site, and no amount and no currency appear anywhere across the pages collected, so no lowest paid price point can be stated. The terms of service do make the user responsible for "any fees or charges associated with your use of the Services (as applicable)", which leaves the possibility of future billing open, but no scale is published today. Users also bear their own mobile and network costs.
Data, GDPR & hosting
A consolidated view of how MarsCode handles your data.
GDPR overview
The privacy policy carries a dedicated section for the European Economic Area, Switzerland and the United Kingdom. It sets out a legal-basis table - contractual necessity, legitimate interest including model training and improvement, legal obligation and vital interests - and lists the rights available: access and copy, rectification, erasure, restriction, portability, withdrawal of consent, objection including to direct marketing, protection against automated decisions, and complaint to a local supervisory authority. Rights are exercised by email at feedback@marscode.com. Transfers out of the region rely on adequacy decisions or the standard contractual clauses adopted by the European Commission. Two representatives are named: Mikros Information Technology Ireland Limited in Dublin for the EEA and Switzerland, and Cosmo Technology Private Limited in London for the United Kingdom. No European data protection officer is appointed, the only one named covering Brazil, and the site never claims compliance in so many words.
Who owns the data?
Section 8 of the terms of service says that, between the user and the publisher, the user owns "Your Content" - the code, text, files, datasets and documentation uploaded to the service - but only subject to the licence granted in return. That licence runs to SPRING (SG) PTE. LTD., its affiliates and its third-party partners, collectively the "SPRING Parties", and it is unconditional, irrevocable, non-exclusive, royalty-free, sublicensable, transferable, perpetual and worldwide, covering reproduction, use and modification. The publisher separately owns the service itself and all "Service Attributes" - the settings, configurations and metadata generated through use - and reserves the right to remove any content or plugin at any time, for any reason or none.
Reuse rights
Because the licence granted to the publisher is non-exclusive and ownership stays with the user, nothing in the terms prevents a user from reusing, publishing or commercialising their own code and the output they obtain: no attribution and no prior permission are required. The counterpart is what the publisher may do in return. The privacy policy, last updated on 26 April 2024, states that profile data, user content, technical information - including keystroke patterns or rhythms - and usage data are collected, and that this material serves to operate the platform, enforce the terms, secure the service and train and improve the publisher's machine-learning models and algorithms. Requests sent to the assistant may be passed to third-party large language models such as Microsoft Azure OpenAI in order to obtain a response. Information is also shared with service providers for hosting, delivery, support, moderation and analytics, with integrated platforms such as Google and GitHub, with entities of the corporate group, and with authorities on a valid legal request. When the plugin runs inside an external editor, its contribution statistics to the user's projects are collected too. Cookies are first-party and strictly necessary, and cannot be declined from the platform itself.
Data retention & training
Hosting summary
The privacy policy states plainly that information is stored on secure servers located in the United States and/or Singapore, and that personal information may be held on a server outside the country where the user lives. No European hosting option is offered, and no broad hosting region is named beyond those two countries. For users in the European Economic Area, Switzerland or the United Kingdom, transfers out of the region are said to rely on appropriate safeguards - adequacy decisions or the standard data protection clauses adopted by the European Commission - and the policy invites enquiries about those safeguards by email. Entities of the publisher's corporate group located abroad are given limited remote access to user information, a point spelled out explicitly for Australian users. One technical detail should be kept separate from the legal one: the website's own IP address resolves to an Akamai content delivery node in Milan. That is content distribution infrastructure, not a place where user data lives, and it must not be read as a European hosting commitment.
Things to keep in mind
Risks and trade-offs to weigh before adopting MarsCode.
- Your code becomes training material: what you type into the assistant can be used to improve the publisher's models, and no exclusion mechanism is offered
- The privacy policy declares the collection of keystroke patterns or rhythms, a behavioural signal that reaches well beyond the code itself
- The licence you grant is perpetual, transferable and sublicensable, and it survives your departure from the service
- Free today does not mean free tomorrow: no price is published, and the terms already reserve fees or charges "as applicable"
- Leaning on generated completions can quietly erode the habit of reading and reasoning about code; treat every suggestion as a draft to review, not as an answer
- The brand is mid-migration to Trae while the legal documents still date from 2024, so what you agree to may not describe what you are actually using
- The cloud environment promised on the homepage was not reachable from the workbench during this review; confirm the capability exists before depending on it
Setup & Integrations
Technical difficulty
Straightforward. Install the extension from the Visual Studio Code Marketplace or the JetBrains Marketplace, restart the editor, then sign in - three steps, documented on the site, with a one-click install link also provided. No server configuration and no API key are required. An account is mandatory but can be opened through Google or GitHub. The only prerequisite is having Visual Studio Code or a JetBrains IDE, and the site links to both download pages. The browser-based route is advertised as needing no download and no configuration at all.
Deployment
Integrations
Supported languages
Behind MarsCode
Resources
All the official URLs gathered for verification and reference.
Frequently asked questions
What is MarsCode?
How much does MarsCode cost?
Which programming languages are supported?
Which editors does the plugin work in?
Is my code used to train the models?
Who owns the code I upload?
Where is my data hosted?
Is there a minimum age?
What is the relationship with Trae?
How do I contact the team?
Should you pick MarsCode?
MarsCode is a credible free option for developers who want AI assistance without leaving the editor they already know. The functional coverage is genuinely broad - completion, generation from natural language, explanation of unfamiliar code, one-click fixes, unit tests, documentation and an autonomous Builder Mode - and the claim of more than 100 supported languages comes with an explicit list of those handled best. The extension is no abandonware either: the JetBrains listing records more than 3.5 million downloads and a release dated 4 August 2026.
The price of that generosity is written in the legal documents rather than on a pricing page. User content feeds the training of the publisher's models and no opt-out is documented. The licence granted to SPRING (SG) PTE. LTD., its affiliates and its third-party partners is perpetual, worldwide, transferable and sublicensable. The privacy policy declares the collection of keystroke patterns. There is no data processing agreement, no subprocessor list and no security certification, and data is hosted in the United States and Singapore only. For a side project or for learning a new language, none of that is disqualifying. For proprietary code under a corporate policy, it very likely is.
Two practical points deserve a check before adoption. First, the brand is in transition: every page title reads Trae, the documentation redirects to docs.trae.ai and the workbench sends visitors to the Trae desktop IDE, so a reader arriving on marscode.com will not always find the name they expected. Second, the browser-based cloud environment still advertised on the homepage was not reachable during this review, the workbench offering only the plugin. Confirm that the capability you came for still exists before building a workflow on it.
- Choosing a selection results in a full page refresh.
- Opens in a new window.