Top Upwork Freelancers

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  1. Arsen S.

    Arsen S.

    VoIP Administration & Development

    Bulgaria - Last active: 3 days ago - Tests: 2 - Portfolio: 6

    I am focused in VoIP field only and I have been working here for more than 8 years. My Area of experiences: VoIP -Asterisk PBX: Full proficiency -FreeSWITCH: Full proficiency -Yate: Full proficiency -Strong knowlege of SIP protocol and SIP routers/proxy servers -OpenSER (Kamailio/OpenSips) -Load Balancing, Least Cost Routing, High Availability, NAT Traversal, Rate and billing systems, etc. -IVR and Auto Attendant Development -Secure VoIP: TLS, SRTP, ZRTP Full proficiency in free Billing/CDR solutions: -A2Billing: Full proficiency (configuration from scratch, customisation) -CDRTool (prepaid billing/accounting and sip tracing for OpenSIPS using RADIUS) -CDR-Stats (call detailed statistic/realtime stat for asterisk and freeswitch) -cgRates (billing for Freeswitch) I provide: - Development of custom Billing and software solutions for Premium Rate Numbers business. - HA and Scalability solutions for existing VoIP networks. - Development and optimisation of VoIP networks/projects. - Ongoing support via request/ticket tracker system. - VoIP Security and Hacker protection solutions. I have successfully completed large amount of commercial installations of VoIP PBX servers. From SOHO to Enterprise deployment including integration of various VoIP solutions into existing network environment. I also have experience in building of secure "bastion" VoIP/Linux servers. Payment Terms: Minimal support package 5 hours. Short-term hourly support: $50 For long-term support please contact for price options. For sizable development projects please contact for price options. We charge upfront scoping (roadmapping meeting, flat-rate). Hourly based projects: -Current hourly rate is $50. Price per projects/feature: -Fixed price projects are calculated based on the hourly rate and expected task complexity. -For all fixed price projects complete project specification with clear tasks description is required -For all fix price projects work will be started only after payment has been es-crowed and both parties have agreed with working terms.

    $55.56 /hr
    175 hours
    4.54
  2. Dmitry S.

    Dmitry S.

    Web, Desktop Developement, Consultant 15+ yrs experience

    Ukraine - Last active: 1 day ago - Tests: 3 - Portfolio: 9

    Areas of Expertise: ✓ Gathering and Analyzing Project Requirements ✓ C#, ASP.NET, MVC 3/4, WebForms, Delphi 1-XE5/Pascal ✓ JavaScript, JQuery, Twitter Bootstrap, Ajax ✓ JSON, JSONP, XML, (D)HTML, HTML5, CSS ✓ Entity Framework, Linq2SQL, NHibernate ✓ MS SQL Server 2005-2012, MySQL, SQLite, Interbase/Firebird, SQL ✓ Crystal Reports, FastReport, QuickReport ✓ SVN, Git, CVS, Atlassian Jira ✓ SOAP, REST, HTTP(S), FTP, TCP/IP, POP/SMTP ✓ Google API, Facebook API, SMS Gateway, Payment Processor ✓ OOP/D, UML, SOLID, Design Patterns, TDD, Agile, SCRUM ✓ Visual Studio 2005-2012, Resharper, dotTrace, FXCope, NUnit, Log4Net

    $25.00 /hr
    1,493 hours
    4.83
  3. Monica Gerchinhoren

    Monica Gerchinhoren

    Mobile Developer and Tester

    Argentina - Last active: 1 day ago - Tests: 1 - Portfolio: 6

    I'm a System Engineer with 10 years of experience. Over the last 6 years I have developed and tested a wide reange of mobile applications in the main platforms iOS and Android. You can check my portfolio and my linked in profile ar.linkedin.com/in/monicagerchinhoren/ Y have several mobile devices phones and tablets I'm very responsible and proactive.

    $13.33 /hr
    1,008 hours
    4.75
  4. Sergey Shubin

    Sergey Shubin

    Expert .NET WPF WCF MVVM Developer

    Bulgaria - Last active: 19 hours ago - Tests: 6 - Portfolio: 18

    Last 20 years I have been programming various kinds of software applications: from simple DOS programs to enterprise-level multi-tier applications. Started with developing C/C++ scientific software, I have moved to business application development and for last 14 years I'm using .NET platform for this purpose. I am a results-oriented developer with extensive experience in C#/VB.NET, WPF, MVVM, WCF, MS SQL Server, Windows Forms, Silverlight. In my work I always use a modern software technology and try to create solutions with the best price/quality ratio. Coding is my passion, and it's just as much fun now as it was when I got my first program to compile...

    $38.89 /hr
    1,485 hours
    4.97
  5. Valentin G.

    Valentin G.

    Software engineer (C/C++, obj-c, Python, Matlab, R, ML algorithms)

    Belarus - Last active: 2 months ago - Tests: 7 - Portfolio: 5

    The last 5 years I have worked mostly as a C and C++ developer in a field of process automation and control (SCADA). Familiar with OOP and TDD, Design Patterns and different methods of software development (waterfall, agile). I have a good experience in the development of multithread client-server applications, windows services, dll-s and cross-platform libraries. One of the specific features of my job was writing readable and easy-portable C-code covered with tests.Another interesting feature is working in small groups dealing with frequently changing goals. The major benefit of this style of work is a great experience on all levels of software development process (from project design and requirement development to final tests). Besides, I have a great interest in the research of new technologies and IT science related fields.

    $25.00 /hr
    549 hours
    5.00
  6. Gennady Svarovskiy

    Gennady Svarovskiy

    Java/C++/Perl professional

    Russia - Last active: 19 hours ago - Tests: 11 - Portfolio: 1

    I am Java developer specializing in web projects and I have good experience with different Java frameworks and technologies including (but not limited to) most popular Spring and Hibernate. Also, I created AJAX front-ends based on jQuery, Bootstrap and DoJo on client side and various REST API frameworks on server side. Besides that I like developing and implementing non-trivial tasks that go beyond traditional CRUD action. Due to good knowledge of GNU/Linux OS (and its most popular daemons: Apache, Tomcat, MySQL/PostgresQL, Postfix/Exim, Named/Bind, iptables) I also can offer full support of application life from initial server setup to continued maintenance after main development is complete.

    Groups: Coding Champs

    $38.89 /hr
    3,009 hours
    5.00
  7. Tabraiz J.

    Tabraiz J.

    Software Architect

    Pakistan - Last active: 2 days ago - Tests: 6 - Portfolio: 7

    To give the very best to my Customers in terms of execution of ideas, honesty and integrity during the application development cycle - perseverance to help them get what they ‘really’ want and never backing out of my commitments. Have been working in the field of IT for the past 15+ years in different roles as programmer, system analyst, software architect and consultant. Expert in most of Microsoft Stack. Well versed in Windows Internals, CLR framework, multi-tier application design and development, threading, Windows systems programming - have been recently working on Android and iOS.

    Groups: Crossrider

    $27.78 /hr
    1,240 hours
    4.98
  8. Sergio S.

    Sergio S.

    JEE Architect - Developer / ExtJS Developer / DBA

    Guatemala - Last active: 19 hours ago - Tests: 5 - Portfolio: 5

    Highly skilled systems architect and developer with more than 30 years of experience designing, developing and deploying applications, from old single platform “green-screen” to multi-tier / distributed systems. Business experience in manufacturing, accounting, distributing, payroll, finance and TELCO: ✔ Strong knowledge of Java SE and JEE stacks, from early versions 1.x up to latest version SE 8 and JEE 7. ✔ Deep understanding of old technologies such Cobol, ISAM, flat files, pipes, “green screen”, etc. This knowledge allowed me to design, code and implement integrations between new applications with legacy ones. ✔ Solid leading and mentoring skills to help and encourage individuals to maximize their productivity by applying the best practices, frameworks, libraries and technology in general. ✔ I'm always learning about new technologies and tools to ease and reduce time spent in application development and deployment. Technology by itself is worth nothing if it does not solve real world problems.

    $45.00 /hr
    695 hours
    5.00
  9. Gaurav B.

    Gaurav B.

    Expert Java,Scala Web Developer(JSF,Spring-MVC,Play,Hibernate,Jquery)

    India - Last active: 3 days ago - Tests: 1

    I have 8+ years of experience and I have worked with large (Oracle) and mid size (Zensar) companies. Languages : Java (6,7,8), Scala, Javascript Frameworks : Java Server Faces, Spring Stack, Java Persistence API, Hibernate, Play! 2, Secure Social, AngularJS, Underscore Technologies : JDBC, JNDI, Primefaces, Servlet, iText, OpenSAML, Apache HTTP Client, Jedis, Jackson, Cognos SDK Github : https://github.com/gaurav-bagga REST API : Google Admin SDK, Windows Azure Directory API, Salesforece API, Zendesk API Databases : MySQL, MS SQL, Apache Derby, Redis, LDAP User Interface : HTML, CSS, Twitter Bootstrap, Require JS Application Servers : Weblogic, Tomcat, Glassfish Testing : Junit, Mockito, Dbunit Build : Maven SCM : Subversion, Git IDE : Eclipse, Netbeans Operating Systems : Windows, Linux, Mac OS X

    $22.22 /hr
    1,405 hours
    4.67
  10. Juan David Gil Diaz

    Juan David Gil Diaz

    Not Another Java Programmer

    Colombia - Last active: 4 days ago - Tests: 6 - Portfolio: 1

    During the last years, I have been working as an employee as well as an academical student/researcher with J2EE Web and J2SE stand-alone environments. During the last year I worked for PSL (www.psl.com.co), CMMI level 5 company qualified for their good practices and awarded with the Software Process Achievement Award by the IEEE and the SEI (Software Engineering Institute). In PSL I developed some modules for a large Web proyect called Impacta, sold to a important motorcycles assembler in Colombia. Impacta is a Web application module that communicates with the company's ERP through Web-services, it has a multi-layer arquitecture that supports a with a CRM like functionality. Impacta uses JSF(Java Server Faces) for its presentation-layer, along with Ajax, in its business-layer uses pure Java integrated with Spring and Web- Services(Xfire) and in its persistence-layer, a PSL's propietary persistence framework was used against an Oracle DB.

    $25.00 /hr
    2,667 hours
    4.95