What Programming Languages Does Palantir Use?

Palantir's main programming languages are Java, TypeScript, Go, and Python. Backend services are written in Java. Web frontends are written in TypeScript with React. Build and deployment tools are written in Go. Data pipelines and most customer-facing code inside Foundry are written in Python, with Scala and SQL for some Spark jobs. Palantir does not publish an internal language census, but its open source repositories on GitHub show the same four languages, and its API framework generates clients in exactly those four.

Palantir Languages by Layer

Java on the Backend

Palantir's platforms are made of hundreds of small services, and those services are written mostly in Java. The clearest public evidence is Conjure, Palantir's open source framework for defining HTTP and JSON APIs. An engineer writes the API once in a YAML file, and Conjure generates the server code in Java and the client code in Java, TypeScript, Go, and Python. Palantir built it so that its many teams could share APIs across those languages.

AtlasDB, Palantir's open source transactional database layer on top of Cassandra, is also Java. Newer services use Kotlin in places, and the Spark jobs that run inside Foundry are often written in Scala or Java.

TypeScript on the Frontend

Foundry, Gotham, and AIP are browser applications, and their interfaces are written in TypeScript with React. Palantir maintains Blueprint, an open source React toolkit for dense, data-heavy interfaces, and uses it for its own products. A frontend engineer at Palantir works in TypeScript every day.

Go for Tooling

Palantir writes its command line and build tools in Go, because Go compiles to a single binary that runs anywhere without an installed runtime. godel, its build system for Go projects, and conjure-go, the Go generator for Conjure, are public. Apollo, the platform that deploys Palantir software into customer and government environments, is operated with tooling in this layer.

Python Inside Foundry

Most code written on top of Foundry is Python. Data engineers write transforms in PySpark, which is the Python interface to the Spark processing engine. Foundry's Code Repositories and Code Workspaces support Python first, and the Ontology SDK lets developers build applications in Python, TypeScript, or Java. Forward deployed engineers, the Palantir role that works on site with a customer, spend much of their time in Python and SQL.

AIP, Palantir's product for connecting large language models to customer data, is also configured in Python and TypeScript. Palantir does not train its own foundation model. AIP connects to models from other providers and to open-weight releases, and the customer chooses which.

What This Means for the Palantir Interview

Palantir's coding rounds allow any mainstream language. Interviewers care about how you decompose a problem and how you respond when the requirements change, and the language is your choice. Most candidates use Python, Java, or C++.

Two rounds test more than syntax. The decomposition round gives you a vague system and asks you to break it into parts. The system design round asks for a data-heavy design, and it is described in what to expect in the Palantir system design interview. The full sequence is in the Palantir interview process, round by round.

Once hired, expect to write Java or TypeScript on a product team and Python on a deployment team. Some deployment roles also require a security clearance, which is explained in whether Palantir requires clearance.

How to Prepare

• Practice in the language you will interview in. Palantir does not restrict the language, so depth in one matters more than breadth. Grokking the Coding Interview teaches the patterns behind the coding rounds.
• Practice decomposition out loud. Take a vague system, name its parts, and state what each part stores and sends. Grokking the System Design Interview covers the data-heavy designs Palantir favors.
• Learn PySpark basics if you want a deployment role. A transform that reads a dataset, joins it, and writes a result is the daily unit of work.
• Prepare the behavioral round separately. The questions are listed in the top Palantir behavioral interview questions.