Updated for Winter ’26 – Java 17 & Mule 4 Enhancements
Last Updated: November 2025 | Exam Version: Winter ’26 (Mule-Dev-201)
This guide reflects the latest Salesforce Certified MuleSoft Developer exam blueprint and Java 17-ready Mule 4 runtimes. Updates include modern API-led connectivity patterns, CloudHub 2.0 deployment best practices, DataWeave improvements, and guidance for building secure, observable integrations in production.
⚡ What’s New for MuleSoft Developer in Winter ’26?
If you previously prepared for MuleSoft Certified Developer – Level 1 (Mule 4), note these key shifts in the Salesforce-branded Mule-Dev-201 exam:
Expect more emphasis on running Mule apps and connectors on Java 17, including compatibility, performance and upgrade considerations.
Stronger coverage of experience / process / system APIs, reusable assets and application networks using Anypoint Platform.
More scenarios around error handling, logging, monitoring and health checks for CloudHub, Runtime Fabric and customer-hosted runtimes.
Salesforce MuleSoft Developer Exam Guide (Mule-Dev-201)
Formerly MuleSoft Certified Developer – Level 1 (Mule 4)
Learn the exam format, domains, Winter ’26 changes and practical tips to pass and validate your skills in APIs & integrations with Mule 4 and Anypoint Platform.
📊 Exam at a Glance – Mule-Dev-201
📝 Recommended Training: Anypoint Platform Development: Fundamentals (DEX401) and hands-on practice building APIs & integrations in a Mule 4 / Java 17 compatible environment.
Exam Objectives & Weightage (Mule-Dev-201 Blueprint)
1. Creating Application Networks & API-led Connectivity
8%Understand API-led connectivity, application networks, and how reusable APIs enable faster delivery. Be able to explain experience / process / system APIs, C4E (Center for Enablement), and how assets are shared via Anypoint Exchange.
View Key Topics ▼
- Characteristics and benefits of API-led connectivity
- Application networks and reuse across projects
- C4E responsibilities and reuse enablement
- Publishing/consuming assets from Anypoint Exchange
2. Designing APIs with RAML & Anypoint Platform
12%Design RESTful APIs using RAML/OAS, define resources, methods, query parameters, data types, examples and documentation in Anypoint Design Center. Understand mocking services and API lifecycle.
View Key Topics ▼
- RAML basics: resources, methods, traits, resourceTypes
- Data types, examples, JSON/XML payload structures
- Design Center projects, mocking services, sharing specs
- Versioning and managing API specs across environments
3. Accessing & Transforming Data with DataWeave
25%Master the DataWeave 2.0 language to transform data between JSON, XML, CSV, Java and other formats. Expect several scenario-based questions on mapping, filtering, conditional logic and error handling in DataWeave scripts.
View Key Topics ▼
- DataWeave script structure (
%dw 2.0, input/output, vars) - Filtering, mapping, reducing and grouping data
- Working with arrays, objects and multi-level transformations
- Error handling, default values and type coercion
4. Connectivity, Routing & Mule Event Processing
30%Build flows and subflows in Anypoint Studio to connect to databases, REST/SOAP services, files, SaaS apps and queues. Understand the Mule event, routing, choice flows, scatter-gather and batch processing.
View Key Topics ▼
- Mule event structure: message, attributes, variables
- Flow vs subflow, private flows, flow references
- Connectors: HTTP, Database, File, JMS, Salesforce etc.
- Routers: Choice, Scatter-Gather, For Each, Batch jobs
- Building REST API implementations from RAML specs
5. Error Handling, Logging & Observability
18%Configure error handling strategies (on-error-continue/on-error-propagate), global error handlers, logging and correlation IDs. Understand best practices for health checks, metrics and monitoring on CloudHub / Runtime Fabric / customer-hosted environments.
View Key Topics ▼
- On-error-continue vs on-error-propagate behavior
- Global vs local error handlers
- Structured logging and log levels
- Health check endpoints and monitoring APIs
6. Deploying & Managing APIs and Integrations
15%Deploy Mule applications to CloudHub, Runtime Fabric or on-prem, and manage APIs with API Manager (policies, SLAs, client apps). Know how to configure properties, secure endpoints and manage versions.
View Key Topics ▼
- CloudHub deployment, workers, properties and logging
- API Manager: applying policies, SLA tiers and contracts
- Managing client applications and credentials
- Versioning APIs and promoting across environments
7. Debugging & Troubleshooting Mule Applications
10%Use Anypoint Studio’s debugger, breakpoints and console logs to troubleshoot flows. Diagnose common connector issues, DataWeave errors and deployment problems.
View Key Topics ▼
- Debugging flows and inspecting Mule events
- Resolving connector configuration and connectivity errors
- Diagnosing DataWeave compilation/runtime issues
- Common CloudHub deployment and runtime errors
📝 Sample MuleSoft Developer Exam Questions
💡 Test Your Knowledge
These questions simulate the style and difficulty of the Mule-Dev-201 exam. Focus on understanding the scenario and why the correct option is best.
Question 1 – API-led Connectivity
Your organization is building a new mobile app that needs customer data from multiple backend systems. You want to design APIs that can be reused by mobile, web and partner channels. According to MuleSoft’s API-led connectivity approach, which design is most appropriate?
A) A single monolithic API directly calling all backend systems
B) Experience APIs calling a process API, which orchestrates system APIs
C) One API per front-end application
D) A single system API that exposes all backend data and logic
✓ Correct Answer: B) Experience APIs calling a process API, which orchestrates system APIs
Explanation: API-led connectivity separates APIs into experience, process and system layers to maximize reuse, governance and agility. Experience APIs are tailored to channels, process APIs orchestrate business logic, and system APIs abstract backend systems.
Question 2 – DataWeave Transformation
A flow receives the following JSON payload:
{
"firstName": "Ana",
"lastName": "Lopez",
"country": "Spain"
}
You must output the string "Lopez, Ana (Spain)". Which DataWeave expression for the body is correct?
A) payload.firstName ++ ", " ++ payload.lastName ++ " (" ++ payload.country ++ ")"
B) payload.lastName ++ ", " ++ payload.firstName ++ " (" ++ payload.country ++ ")"
C) payload.country ++ " - " ++ payload.lastName ++ " " ++ payload.firstName
D) write(payload, "application/java")
✓ Correct Answer: B) payload.lastName ++ ", " ++ payload.firstName ++ " (" ++ payload.country ++ ")"
Explanation: The requirement is LastName, FirstName (Country). Option B concatenates the fields
in the correct order using the DataWeave string concatenation operator ++.
Question 3 – Error Handling
A flow calls an external REST service. If the service returns HTTP 500, you want to log the error, set a friendly message, and continue processing the flow with a default response instead of failing the entire flow. Which configuration is most appropriate?
A) Wrap the HTTP Request in a Try scope with on-error-propagate
B) Global error handler with on-error-propagate and rethrow
C) Local error handler with on-error-continue, logger and Set Payload
D) No error handler – let Mule’s default error handler manage it
✓ Correct Answer: C) Local error handler with on-error-continue, logger and Set Payload
Explanation: on-error-continue handles the error and resumes the flow, allowing you to log the
issue and set a fallback payload. on-error-propagate would propagate the error and typically fail the flow.
Question 4 – Deployment & Properties
You are deploying a Mule application to CloudHub with different database credentials for dev, test and prod. What is the recommended way to manage these values?
A) Hard-code the credentials in the flow for each environment
B) Use a DataWeave script to compute the credentials at runtime
C) Store credentials in externalized property files or secure properties per environment
D) Store credentials directly in the RAML specification
✓ Correct Answer: C) Store credentials in externalized property files or secure properties per environment
Explanation: Using externalized properties (such as CloudHub properties or secure property placeholder files) is a best practice for managing environment-specific values like credentials.
Question 5 – Connectors & Integration
A flow must read records from a CSV file on an SFTP server and insert them into a database table. Which sequence of components represents the most appropriate design?
A) Scheduler → File connector → Logger → Database connector
B) SFTP connector → Transform (DataWeave) → Database connector (bulk insert)
C) HTTP Listener → Database connector → File connector
D) Database connector → JMS → SFTP connector
✓ Correct Answer: B) SFTP connector → Transform (DataWeave) → Database connector (bulk insert)
Explanation: The SFTP connector retrieves the CSV file, DataWeave transforms the records into the target structure, and the Database connector performs inserts (ideally in bulk) into the table.
💡 Exam Tip: The Mule-Dev-201 exam is very scenario-driven. You must pick the option that best reflects MuleSoft best practices (reuse, properties, security, error handling) rather than just what is technically possible.
📚 Study Resources & 4–6 Week Plan
🎯 Recommended Study Plan
Complete Trailhead + official MuleSoft training basics on API-led connectivity, RAML/OAS, Anypoint Platform and Mule 4 fundamentals.
In a dev org, build at least 2–3 end-to-end APIs (system + process + experience layers), including DataWeave transformations and CloudHub deployment.
Take multiple full-length practice exams. Review every incorrect question, re-implement flows in Studio, and memorize key DataWeave patterns.
💡 Exam-Day Tips for Mule-Dev-201
120 minutes for 65 questions ≈ ~1.8 minutes per question. Don’t overthink simple scenario questions; mark complex ones for review.
Prefer solutions that use properties, reuse, layered APIs, proper error handling and avoid hard-coding or tightly-coupled designs.
For tough questions, first remove obviously incorrect answers (e.g., credentials in code or RAML), then choose the remaining option that aligns best with MuleSoft reference architecture.
❓ Salesforce MuleSoft Developer – FAQ
1. Who should take the Salesforce MuleSoft Developer exam?
This exam targets developers and integration engineers who build APIs and integrations with Mule 4 and Anypoint Platform. 6–12 months of hands-on Mule experience is ideal.
2. Is this the same as “MuleSoft Certified Developer – Level 1 (Mule 4)”?
It’s the Salesforce-branded successor with updated objectives, code Mule-Dev-201. The core skills (API-led design, DataWeave, connectors, deployments) are similar, but the blueprint now reflects newer runtimes and platform capabilities.
3. How hard is the MuleSoft Developer exam compared to Salesforce Platform Developer I?
Difficulty is comparable, but the focus is different. Mule-Dev-201 emphasizes integration patterns, APIs, runtimes and DataWeave, whereas PD1 centers on Apex, triggers and the Salesforce data model. If you enjoy integrations and APIs, this exam feels more natural.
4. How long should I prepare for Mule-Dev-201?
With prior Mule experience, 4–6 weeks of focused study plus hands-on practice is realistic. If you are new to integrations or MuleSoft, plan closer to 8–10 weeks and build at least a few end-to-end projects.
5. What happens after I pass – do I need maintenance modules?
Yes. Salesforce typically requires periodic maintenance tasks on Trailhead when new releases arrive (for example Winter / Spring). These are short modules you complete to keep your MuleSoft Developer credential active without re-taking the full exam.
6. Which exam should I take next after MuleSoft Developer?
Common next steps are MuleSoft Developer II (for advanced integrations) or the MuleSoft Hyperautomation Developer and integration architect certifications, depending on whether you want to go deeper technically or move toward architecture.