דרושים » ניהול ביניים » NodeJS - backend Engineer

משרות על המפה
 
בדיקת קורות חיים
VIP
הפוך ללקוח VIP
רגע, משהו חסר!
נשאר לך להשלים רק עוד פרט אחד:
 
שירות זה פתוח ללקוחות VIP בלבד
AllJObs VIP
כל החברות >
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time and Hybrid work
A Security company is seeking a skilled and experienced software engineer with expertise in Node.js and cloud infrastructures, to join our dynamic team. As a software engineer, you will play a crucial role in developing and maintaining robust, scalable, and high-performance software solutions. The ideal candidate should have a strong background in Node.js development, along with a deep understanding of platform engineering and cloud software architecture.
Requirements:
5+ years of experience as a backend Engineer with an emphasis on Node.js development

Proficiency in working with cloud platforms (e.g., AWS, Azure, GCP)

Strong understanding of platform operations, infrastructure, and high-scale environments

Experience with containerization and orchestration tools (e.g., Docker, Kubernetes)

Solid understanding of database systems (SQL and NoSQL)

Excellent problem-solving and debugging skills

Strong communication and collaboration skills

BSc in Computer Science or equivalent experience

Experience with React to build components for customer-facing applications Advantage

Knowledge in Golang Advantage

Familiarity with DevOps practices and tools Advantage

Working experience in a Cybersecurity company Advantage
This position is open to all candidates.
 
Hide
הגשת מועמדות
עדכון קורות החיים לפני שליחה
8145081
סגור
שירות זה פתוח ללקוחות VIP בלבד
משרות דומות שיכולות לעניין אותך
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time
As a Software Developer you will be responsible to:

Play a key role in designing and implementing infrastructure solutions to support our development and deployment processes. This role requires a versatile individual with strong technical skills, an out-of-the-box thinker, and a passion for solving challenging problems in cloud-based environments.

Key Responsibilities:
Develop, maintain, and optimize Python-based services and tools for cloud platforms (AWS preferred).
Design and implement scalable and secure infrastructure solutions, leveraging modern cloud technologies.
Build and maintain APIs, microservices, and server-side applications using Python frameworks.
Collaborate with cross-functional teams to integrate CI/CD pipelines and improve deployment efficiency.
Troubleshoot and resolve technical bottlenecks in cloud-based systems.
Contribute to system architecture design and ensure best practices are followed.
Stay up-to-date with emerging technologies and trends to continuously improve development and deployment processes.
Requirements:
Requirements
5+ years of professional experience as a backend developer, with strong skills in Node.js (TypeScript preferred)
Solid experience in developing services on cloud platforms, particularly AWS (experience with Azure or GCP is a plus)
Expertise in Node.js frameworks (e.g., Express)
Strong understanding of software engineering principles, including system design and data structures
Experience building RESTful APIs and microservices architectures
Familiarity with relational and NoSQL databases (e.g., MySQL, MongoDB)
Strong debugging, performance optimization, and troubleshooting skills
Strong communication and collaboration skills, with the ability to work effectively in a team
Proactive, detail-oriented, and self-motivated with the ability to thrive in a fast-paced environment
Willingness to work on some Python-based components as part of the role

Nice-to-Have:
Proficiency in Python.
Knowledge of serverless architecture (e.g., AWS Lambda).
Experience with DevOps tools and practices, including: Infrastructure as Code (IaC) tools like Terraform.
Containerization and orchestration tools like Docker and Kubernetes (K8s)
CI/CD tools such as Jenkins or similar.
Knowledge of security best practices for cloud-based environments.
Previous experience working in an infrastructure or architecture team.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8317771
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
03/09/2025
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time
Were looking for a Senior Software Engineer to join our growing R&D team. In this role, you will play a critical part in designing, building, and optimizing complex systems that power our AI-driven platform. Youll work across the stack- primarily on backend services - with opportunities to influence architectural decisions and build highly scalable and performant systems. Youll collaborate closely with AI, product, and frontend teams to bring advanced features to life and ensure a seamless, intelligent experience for our users.

This is a high-impact role for someone who is passionate about engineering excellence, eager to shape systems end-to-end, and ready to grow with a fast-moving, AI-first company.



Key Responsibilities:

Design, develop, and maintain robust backend systems and services.
Ensure the scalability, performance, and security of backend components.
Collaborate with front-end developers and data teams to integrate user-facing elements with server-side logic.
Optimize the platform's infrastructure to handle large-scale data processing and analysis.
Troubleshoot and debug complex issues, identifying and implementing the most effective solutions.
Contribute to the architecture and system design decisions for the backend infrastructure.
Stay up to date with industry trends and new technologies to continuously improve backend performance.
Requirements:
7+ years of software development experience in a fast-paced SaaS environment.
Strong experience with server-side technologies, particularly Node.js, Python and SQL.
In-depth knowledge of databases; experience in schema design and optimization.
Expertise in API development and microservices architecture.
Familiarity with cloud platforms such as Google Cloud/AWS.
Understanding of containerization and orchestration tools (Docker, Kubernetes).
Experience with message queues (e.g., RabbitMQ, Kafka or their cloud alternatives such as SQS/pubsub) and data processing.
Experience with client-side technologies (e.g. React) is a plus
Applied AI or video editing knowledge is a big plus.
Excellent problem-solving skills with a focus on scalability and performance.
Ability to work independently while also thriving in a collaborative team environment.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8331691
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
10/08/2025
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time
We are looking for a Staff Engineer.
What Youll Do:
Lead architecture and system design for critical components of the Developer Experience platform, ensuring scalability, resilience, and long-term maintainability.
Own end-to-end delivery of complex initiatives, from requirements gathering and design to implementation, rollout, and observability.
Design, implement, and maintain robust microservices supporting high-throughput and low-latency operations.
Define and uphold API design standards, including gateway configuration, versioning strategy, and long-term lifecycle management.
Build and optimize backend systems that enable developer-facing products such as SDKs, APIs, and webhooks.
Work with both relational and NoSQL databases to ensure data consistency, scalability, and performance.
Collaborate with cross-functional teams to design systems that meet operational and business requirements.
Research and implement cloud-native architectures to support growth and scalability.
Contribute to the creation of developer tools and standards that improve the usability of our APIs and SDKs.
Requirements:
10+ years of experience in backend development, with a strong focus on scalable infrastructure.
Proficiency in Node.js and TypeScript; additional experience with other backend languages is a plus.
Strong expertise in relational and NoSQL databases, including schema design, query optimization, and troubleshooting.
Experience designing and managing RESTful APIs, including versioning strategies, API gateway integration, and developer-first design.
Proven experience designing and deploying microservices-based architectures in production environments.
Hands-on experience with cloud providers (AWS, GCP, Azure) and container orchestration tools (e.g., Kubernetes, Docker).
Solid understanding of system design principles, distributed systems, and scalability.
Experience with monitoring and logging frameworks (e.g. Datadog, Prometheus, Grafana, ELK stack).
Deep understanding of REST APIs and event-driven architectures.
Advantage - Familiarity with AWS, Servers-less
Strong problem-solving skills, with the ability to troubleshoot production issues effectively.
Ability to manage multiple priorities and thrive in a service-oriented, fast-paced environment.
Bonus Points:
Experience designing developer-centric SDKs, tools, or CLI utilities.
Track record of contributing to internal platform teams or DX-focused initiatives.
Knowledge of OpenAPI/Swagger specifications and API documentation best practices.
Passion for elevating developer experience and usability across engineering platforms.
Hands-on experience in designing developer-friendly SDKs and APIs.
Knowledge of CI/CD pipelines and best practices for automated testing and deployment.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8296063
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time
We are looking for a Senior DevOps Engineer to join our R&D team in developing the next rising product in the health tech landscape. If you are looking for a challenging, influential position and are passionate about making an impact, this might be the role for you.
As a Senior DevOps Engineer , youll play a key role in the design, development, testing, deployment, and monitoring of our infrastructure and products. In this position, you'll make significant contributions to our observability stack, helping build and maintain robust systems for logs, metrics, traces, and alerting.
Our ideal candidate is passionate about DevOps and observability, has strong communication skills, and thrives on constant improvement for both technology and processes. If you enjoy working on multiple projects in parallel and are a proactive team player, youll fit right in.
This is a unique opportunity to join the core team of a fast-growing startup, where your contributions will have a direct impact on our product and success.
Responsibilities:
Support and collaborate with cross-functional engineering teams using cutting-edge technologies.
Contribute to the design, implementation, and maintenance of monitoring, logging, and alerting systems (e.g., Prometheus, Grafana, Loki)
Secure, scale, and manage our cloud environments (AWS and GCP)
Design and implement automation solutions for both development and production
Manage and improve our CI/CD pipelines for fast and safe delivery
Lead best practices in infrastructure, observability, configuration management, and system hardening
Continuously assess and improve existing infrastructure in line with industry standards
Requirements:
BSc in Computer Science, Engineering, or equivalent experience
5+ years of experience as a DevOps Engineer or similar software engineering role
Proven experience with Docker and Kubernetes (EKS preferred)
Hands-on experience with monitoring and observability tools, including Prometheus, Grafana, Datadog, or similar.
Expertise in Terraform for AWS infrastructure-as-code deployments
Strong collaboration and interpersonal communication skills
Excellent analytical thinking and problem-solving mindset
Proficiency with relational databases
Solid knowledge of Python and Bash scripting
Experience with test automation an advantage
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8320472
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
01/09/2025
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time
We are seeking an experienced Senior Backend Engineer with a passion for tackling complex challenges across a diverse range of technologies. Your role will involve a deep commitment to software design, code quality, and performance optimization. As part of our Engineering team at Dream, your mission will be to empower critical infrastructure by enabling the detection, investigation, and response to complex attacks and data breaches on their networks.

As a Senior Backend Engineer, you will take a lead role in developing the backend infrastructure to efficiently handle, process, and store massive volumes of data. Your expertise will play a crucial part in building a scalable, high-performance backend system that serves as the foundation for other services within the platform. Additionally, you will be responsible for translating intricate requirements into meticulous and actionable backend designs.

Responsibilities
Be a significant part of the development of backend infrastructure to efficiently handle, process, and store vast volumes of data.
Architect and build a scalable, high-performance backend system that supports various services within the platform.
Translate intricate requirements into meticulous backend design plans, maintaining a focus on software design, code quality, and performance.
Collaborate with cross-functional teams to implement backend and data-handling techniques.
Apply your expertise to create robust backend solutions.
Leverage your proficiency in cloud platforms such as AWS, GCP, or Azure to drive strong backend engineering practices.
Demonstrate strong debugging skills, identifying issues such as race conditions and memory leaks within the backend system. Solve complex backend problems with an analytical mindset and contribute to a positive team dynamic.
Bring your excellent interpersonal skills to foster collaboration and maintain a positive attitude within the team.
Requirements:
5+ years of experience with server-side coding in Java, Python, Go, or .NET.
Experience with microservices architecture and tools (docker, k8s, etc.).
Experience with large-scale applications with large data volumes and intensive traffic.
Experience with NoSQL databases.
Experience with bootstrapping projects and building systems from scratch.
Proven ownership and leadership skills.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8327583
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
Location: Tel Aviv-Yafo
Job Type: Full Time
We are looking for a Senior Full Stack Engineer with a strong backend orientation and deep Python experience who excels at solving complex challenges and is passionate about building robust, scalable, and data-driven systems. In this role, you will work closely with a talented team of engineers, Product, Design, and Data Science to deliver innovative solutions that have a meaningful impact on users' lives.

As a senior engineer, you will take ownership of projects from concept to deployment in a fast-paced, highly collaborative environment. Youll focus primarily on backend development, with the ability to contribute to frontend work as needed. Youll also mentor team members and help drive technical excellence.

Responsibilities:
Backend Development: Design, implement, and maintain scalable, efficient, and secure backend services, with a focus on Python and Node.js.
Data Infrastructure: Work with real-time data systems, including Elasticsearch, Vector Databases, and other high-performance storage and retrieval tools.
End-to-End Feature Development: Deliver features across the stack, integrating frontend and backend components.
Collaborate with Data Science to integrate advanced algorithms and ML models into production systems.
Partner with Product Managers and Designers to brainstorm and execute impactful product features.
Ensure system architecture is reliable, maintainable, and built for scale.
Lead by example: contribute to code reviews, mentor peers, and foster engineering best practices.
Stay up to date with emerging technologies and suggest ways to apply them for performance and scalability improvements.
Requirements:
5+ years of professional experience as a Full Stack or Backend Engineer.
Strong hands-on experience with Pythona must.
Proven experience designing and maintaining complex, scalable systems in productionmust.
Experience working with real-time data pipelines, Elasticsearch, and Vector DBsa strong advantage.
Experience with Node.jsan advantage.
Frontend experience with ReactJS or React Nativenice to have.
Deep understanding of algorithms, data structures, and system optimization.
Strong experience with both relational and non-relational databases (e.g., PostgreSQL, MongoDB).
Familiarity with AWS, Docker, Kubernetesan advantage.
Excellent collaboration and communication skills, with a proactive and impact-driven mindset.
BSc in Computer Science or a related fieldor equivalent hands-on experience.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8327536
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
03/09/2025
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time
We are seeking a Backend Engineer, passionate about AI and image editing to join our elite team and play a key role in Backend Engineering, MLOps, and Data Engineering, driving innovation and efficiency.
Responsibilities
Developing and optimizing scalable, distributed systems on cloud infrastructure (AWS/GCP/Azure), encompassing storage solutions, servers, and APIs.
Enhancing application efficiency for increased scalability and performance.
Implementing robust security measures to protect data integrity and privacy.
Collaborating with cross-functional teams to integrate backend systems with front-end platforms for a seamless user experience.
Conducting code reviews and ensuring adherence to best coding practices.
Monitoring and improving system health and performance, including troubleshooting and debugging issues.
Requirements:
4 years of experience as a Backend Engineer.
B.Sc in computer science, software engineering or a related field, from a well known university.
Proficiency in at least one major cloud platform - AWS, GCP, or Azure.
Proven expertise in backend server development, using languages like Python, Scala, Go, or Java.
Experience with developing and maintaining distributed systems.
Experience designing RESTful APIs.
​​Experience working with SQL or NoSQL databases.
Familiarity with Agile methodologies and CI/CD pipelines - an advantage.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8332131
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
05/08/2025
Location: Tel Aviv-Yafo
Job Type: Full Time
ShiftLeft is building the cloud security platform for developers (CAS). Our platform empowers teams to find, fix, and prevent security risks in application code and infrastructure as code through automation and security-as-code principles. We're looking for a skilled Senior Backend Engineer to join our team and contribute to our Cortex Cloud platform.
As a Senior Backend Engineer, you'll have a high-impact role in shaping the future of our code security products. Beyond building robust and scalable backend features, you'll help drive performance, reliability, and innovation across our systems. Our team leads the way in owning both the departments core infrastructure and Developer Experience (DevEx), empowering the entire engineering organization with powerful internal platforms and tooling. If you're excited by technical challenges, meaningful ownership, and making life easier for developers this is the place for you.
Your Impact
Feature Development: Design, build, and maintain robust backend services using TypeScript/Node.js. Take full ownership of complex, cross-system features from initial requirements through architecture, implementation, and deployment.
Build and Optimize Scalable Systems: Ensure performance, reliability, and cost-efficiency across distributed systems through thoughtful design, deep observability, and continuous optimization.
Platform Engineering & DevEx: Drive platform engineering initiatives by developing the department infrastructure and shared tooling that boost scalability, reliability, and the developer experience across the department.
Own Core Infrastructure: Design, operate, and evolve the departments infrastructure stack including BigQuery, MongoDB, Redis, and Argo Workflows using cloud-native technologies like Terraform, Kubernetes, and Helm.
Requirements:
4+ years of experience in backend development, with a strong foundation in designing and maintaining scalable systems.
2+ years of hands-on experience with TypeScript and Node.js in production environments.
Proven experience working with cloud platforms such as GCP (or equivalent like AWS/Azure).
Familiarity with Kubernetes
Familiarity with operating live production systems at scale, with a focus on reliability and performance.
Strong problem-solving skills and a passion for continuous learning and technical excellence.
Bachelors degree in Computer Science, Engineering, or a related field or equivalent military experience.
Advantage
Experience developing security-related products, especially in the code analysis or AppSec domain.
Familiarity with Infrastructure as Code tools such as Terraform or CloudFormation.
Hands-on experience with Argo Workflows or similar orchestration platforms.
Security knowledge
Orchestrated and managed containerized applications using Kubernetes, including deployment, scaling, and self-healing of microservices.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8290735
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
11/08/2025
חברה חסויה
Location: Tel Aviv-Yafo
Job Type: Full Time
An innovative network security solutions provider, is at an exciting time in its history and is growing fast! We are looking for a highly skilled and versatile Backend Engineer to join our development team. As a Backend Engineer, you will be responsible for designing, developing, and maintaining the backend infrastructure and components of our platform. As part of your role, you will also work on the frontend aspects of our platform and collaborate with stakeholders and cross-functional teams to optimize full-cycle system performance
Responsibilities:
Design, develop, and maintain backend systems and APIs to support our web applications
Implement and optimize data storage solutions, including databases, to ensure efficient and reliable data management
work closely with front-end developers to integrate backend functionalities and ensure a seamless user experience
Collaborate with product managers, stakeholders, and cross-functional teams to gather requirements, translate them into technical specifications, troubleshoot and resolve backend-related issues, and optimize system performance.
Requirements:
Bachelor's degree in computer science, Software Engineering (or equivalent work experience) - must
4 + years of experience as a software engineer with hands-on production experience working in the backend side of complex systems
Experience with cloud services (GCP/AWS/Azure)- must
Strong proficiency in at least one backend programming language (e.g., Go, JAVA or C#) and associated frameworks
Hands-on experience in the following technology stack: Kubernetes & Helm, Elasticsearch
Experience with relational databases (PostgreSQL- advantage), and ability to design efficient schemas and write optimized queries
Strong problem-solving skills and ability to work both independently and as part of a team
Excellent communication and interpersonal skills, with the ability to effectively collaborate with cross-functional teams
Low-level understanding of network protocols and Windows internals- advantage.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8298971
סגור
שירות זה פתוח ללקוחות VIP בלבד
סגור
דיווח על תוכן לא הולם או מפלה
מה השם שלך?
תיאור
שליחה
סגור
v נשלח
תודה על שיתוף הפעולה
מודים לך שלקחת חלק בשיפור התוכן שלנו :)
24/08/2025
Location: Tel Aviv-Yafo
Job Type: Full Time and Hybrid work
As a Backend Engineer in our platform team, You'll take part in our effort to improve our product, productivity, security and the ability to scale. Opportunity to make a significant impact by driving the technical direction of a high-growth company.
As a Backend Engineer, you will:
Develop and maintain policies and procedures for software development, deployment, and maintenance. Monitor cloud environments using infrastructure as code methodologies.
Work closely with other development teams to ensure that our software applications meet the needs of the organization.
Participate actively in code reviews to uphold high standards of quality and maintainability in software development.
Stay up-to-date with emerging trends and technologies and assess their potential impact on our organization.
Requirements:
Qualifications:
Bachelors degree in Computer Science, Engineering, or equivalent experience.
3+ years of hands-on experience in backend development, with expertise in Python.
Proficiency in Python, with a solid grasp of its ecosystem and best practices
Experience developing scalable, reliable components in production environments.
Familiarity with cloud platforms (AWS preferred).
Familiarity with containerization tools such as Docker and Kubernetes.
Strong analytical skills with the ability to diagnose and resolve complex technical issues.
Experience researching, evaluating and integrating new technologies within existing codebases is a big plus.

Advantages:
Experience with Pydantic, SQLAlchemy and FastAPI.
Experience researching, evaluating and integrating new technologies within existing codebases.
This position is open to all candidates.
 
Show more...
הגשת מועמדותהגש מועמדות
עדכון קורות החיים לפני שליחה
עדכון קורות החיים לפני שליחה
8315886
סגור
שירות זה פתוח ללקוחות VIP בלבד