Pacs open source codemunkák

Szűrő

Legutóbbi kereséseim
Szűrés erre:
Költségvetés
eddig:
eddig:
eddig:
Típus
Készségek
Nyelvek
    Munka státusza
    2,000 pacs open source code munka, árazás ebben: EUR

    Olyan személyt,személyeket keresek akik egy cég webshopjának folyamatos fejlesztésében részt tudnak venni! Fontos, hogy az illető(k) nagy tapasztalattal rendelkezzenek az Open Cart és a web(kereskedelem) terén. Feladatok: ckeditor, termék szűrő, termékadatlap és más feladatok.

    €1007 (Avg Bid)
    €1007 licitátlag
    7 árajánlat

    Via emailKedves Ábel! Beszélgetésünkre hivatkozva szeretnélek megkérni, hogy egy 45 perces szettet összerakni szíveskedj, amit fel tudok majd használni első spinning órámon. Tervezett órám az alábbiak szerint nézne ki (zárójelben a bpm szám). 1. SIK ÜLVE (90-110 PM) BEMELEGÍTÉS KB 5 PERC 2. JUMPOK (90 BMP) ÁTMOZGATÁS KB 5 PERC-7 PERC BENNE 4,8,16 JUMP 3. ÁLLVA HEGYEN (75 BMP) KB 7 PERC 4. ÜLVE HEGY (65 BMP) KB 5 PERC ERŐS ELLENÁLLÁS 5. SIK ÜLVE (90 BMP) KB 5 PERC 6. FUTÁS (80-90 BMP) KB 3 PERC 7. ÁLLVA HEGYEN (75 BMP) 5 PERC 8. JUMPOK (85 BMP) 5 PERC 9. FUTÁS VÉGÉRE (...

    €88 (Avg Bid)
    €88 licitátlag
    2 árajánlat

    Weboldalra van szükségem Tervezés és létrehozás Online áruház Honlap készítés céljából keresek profit. Cégünk lakókocsik gyártásával foglalkozik. Gyártunk még utánfutókat valamint ezek alkatrészeit forgalmazzuk.

    €962 (Avg Bid)
    €962 licitátlag
    22 árajánlat
    code needed Véget ért left

    asdcbadsk;c hjavsdk;hbasjkd jksab jksad kjbsakj bjasb jkbsjk baskjb sbjk bdskj kjds kjdskj jkd kjdbc kjbsdj bjksdbc jdsb j

    €28 (Avg Bid)
    €28 licitátlag
    1 árajánlat

    Tisztelt Kockatt! Youtubra kellene indexkép. Heti kb 20 db. Adnék egy képet, amit meg kellene csinálni az én fotóimból.

    €14 / hr (Avg Bid)
    €14 / hr licitátlag
    7 árajánlat

    linképítést, cikk beküldést szeretnék román oldalakra. Az oldalam román nyelvű és zenével foglalkozik.

    €102 (Avg Bid)
    €102 licitátlag
    10 árajánlat

    Job for people from Hungary,Serbia,Croatia. Pozdrav, trazim developera koji ima iskustva u editovanje WP tema i Paymen system ( Woocommerce) Na primer: Dodati jos 3 sekcija u WP theme,Editovati Woocommerce plugin. Üdvözlet, Wordpress Woocommerce plugin módositásában jártas szakembert keresek projekt munkára. Ha nem okoz neked gondot,hogy a WP témát kibővisd pl: 3 új 'section'-al vagy kicseréld a fizetési rész stilusát, akkor nyugodtan jelentkezz.

    €140 (Avg Bid)
    €140 licitátlag
    6 árajánlat

    ezeket a tapasztalatokat kellene magyarra fordítani. Annyi lenne még fontos hogy a US mértkékegységeket, át kellene váltani a nálunk használatosra a szövegben. lbs, pund, stb helyet... liter, kg, stb...

    €7 - €14 / hr
    €7 - €14 / hr
    0 árajánlat

    Kedves Annamária! Egy váci székhelyű start-up vállalkozás számlaképes marketinges munkatársat keres. Feladat: marketing stratégia, offline-online marketing, seo, adwords, stb Hencz Imre 06 70 949 14 13

    €14 - €23 / hr
    €14 - €23 / hr
    0 árajánlat

    http://www.vaguthu.mv/ramazan1436/litus-nala-nala-raajje-photo-challenge/#view=vote&for=8072626 http://www.vaguthu.mv/ramazan1436/litus-nala-nala-raajje-photo-challenge/#view=vote&for=8072664 http://www.vaguthu.mv/ramazan1436/litus-nala-nala-raajje-photo-challenge/#view=vote&for=8132271 http://www.vaguthu.mv/ramazan1436/litus-nala-nala-raajje-photo-challenge/#view=vote&for=8132275 http://www.vaguthu.mv/ramazan1436/litus-nala-nala-raajje-photo-challenge/#view=vote&for=8132273 200 Each

    €25 / hr (Avg Bid)
    €25 / hr licitátlag
    5 árajánlat

    Kedves BMDseoprovider, láttam a profilját, és szeretném felajánlani Önnek a projektem. Kérem, nézze meg a projektleírást, és beszéljük meg a részleteket.

    €58 (Avg Bid)
    €58 licitátlag
    9 árajánlat

    kjfgdfhmngklnlg;retgoifdjgiohujgikpofgkhopigtr09kodtigjbyhiortjdmobgjkljk bxniogk,nypokf[pyo9tcholfb

    €28 - €232
    €28 - €232
    0 árajánlat

    A mellékelt képen látható kakast kellene lemodellezni, 3D nyomtatáshoz On the attached picture need 3d modell to 3d print. .ply

    €41 (Avg Bid)
    €41 licitátlag
    2 árajánlat

    Kedves Gergob (Gergő?), OpenERP fejlesztési projektek kapcsán próbáljuk bővíteni elsősorban fejlesztői erőforrásainkat (azonnali kezdéssel), de elképzelhető, hogy a közeljövőben technológiai vezetőre és business analystre is szükségünk lesz. Érdekelne esetleg az együttműködés?

    €8118 (Avg Bid)
    €8118 licitátlag
    3 árajánlat

    helló alkalmazz engem a projektedben és garantáltan elégedett leszel. .

    €7 - €14 / hr
    €7 - €14 / hr
    0 árajánlat

    Special tudás a lakberendezés terén. A munkahelyemen lakberendezéssel foglalkozok és szeretnék önnél is probálkozni mivel szeretem ezt a szakmát

    €140 (Avg Bid)
    €140 licitátlag
    2 árajánlat

    Mellékelten küldöm önéletrajzomat. Sajnos idegen nyelven nem beszélek, csak magyarul. Várom válaszukat.

    €136 (Avg Bid)
    €136 licitátlag
    1 árajánlat

    EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon EC2 Amazon

    €244 (Avg Bid)
    €244 licitátlag
    1 árajánlat

    Az EMKA Tanácsadó Kft és Hajdúnánás Önkormányzata egy szakmai gyakorlati/gyakornoki programot indít hajdúnánási, felsőoktatási intézményben tanuló diákok számára. A gyakorlatot településfejlesztés, településmarketing területen lehet teljesíteni. A program neve: HIDAK. A program számára szeretnénk egy logót terveztetni. A leendő résztevőknek készült felhívást (a helyi újságban és a Facebookon jelent meg).

    €60 (Avg Bid)
    €60 licitátlag
    6 árajánlat

    Create a Banner Create a Banner Create a Banner Create a Banner Create a Banner Create a Banner Create a Banner Create a Banner

    €6 / hr (Avg Bid)
    €6 / hr licitátlag
    2 árajánlat

    xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo xazoo

    €28 - €232
    €28 - €232
    0 árajánlat
    Conversion of PHP code to Python 6 nap left
    HITELESÍTETT

    I have a backend code for a pre-existing fully function website and mobile app. The backend code is currently all written in php. I need someone to convert this existing php code into fully functional python code which I can deploy.

    €29 (Avg Bid)
    €29 licitátlag
    13 árajánlat

    ...interested in is an open floor plan, which should create a spacious, interconnected living environment. Key features to consider: - Modern design aesthetic: The overall look and feel of the home should be modern, with clean lines and sleek finishes. - Open floor plan: This is a must-have for the project. The design and layout should facilitate an open, airy feel throughout the home. - Functional design: The architecture should not only be aesthetically pleasing, but also practical and functional for everyday living. - Quality of work: Attention to detail and high-quality workmanship are essential. Ideal skills for this project would include: - Proven experience in new residential construction projects - Strong background in modern architecture and design - Experti...

    €6109 (Avg Bid)
    €6109 licitátlag
    30 árajánlat

    ...some existing C++ code for a virtual camera system. The code I currently have is in C++ and designed to operate on Windows. Key aspects of the project: - **Adaptation**: The task is to take this existing code and modify it to allow the user to switch between different camera modes. I have a specific vision for this system which includes switching between: - The system camera - The system camera with a watermark - A full-screen image - **Functionality**: The change between these modes should be quick and seamless, and should be implemented through keyboard shortcuts. The user should be able to easily navigate and switch between these modes without any lag or glitches. —— more information: I would like you to adapt some code for a simpl...

    €148 (Avg Bid)
    €148 licitátlag
    15 árajánlat

    I'm in need of a Python programmer to write a piece of code for me in Python, and then compile a detailed report about it. The job essentially involves writing a code in Python, and then the creation of a detailed report about the code, its structure, design, and implementation. Key Requirements: - Proficiency in Python programming - Strong understanding of coding best practices - Experience in technical report writing - Ability to explain complex concepts in a clear and concise manner - Familiarity with creating and structuring PDF documents. Ideal deliverables: - A well-structured Python code - A detailed, structured, and easy to understand report in PDF format. If you're confident in your Python programming skills and technical writing abil...

    €118 (Avg Bid)
    €118 licitátlag
    26 árajánlat

    The project aims to develop a software system that can track and control the cursor movement on a computer screen using the user’s eye movements. The system would use an eye-tracking device to monitor the user’s eye movements and pupil detection, head and eye tracking, cursor position prediction, calibration, performance tuning, and adaptive learning techniques to translate them into cursor movements. The system would be beneficial for individuals with physical disabilities or limited mobility, providing them with an alternative and accessible way to interact with a computer interface. The system would also offer a more natural and intuitive way to control the cursor using the natural movement of the eyes. The system would employ computer vision techniques provided by OpenCV, a...

    €83 (Avg Bid)
    €83 licitátlag
    7 árajánlat
    Python Playwright Code Finishing 6 nap left
    HITELESÍTETT

    I'm seeking a Python developer with experience in Playwright to complete my existing code. Key tasks include: - Reviewing the existing codebase. - Identifying and fixing bugs. - Completing partial functionalities if any. Ideal candidate should have: - Prior experience with Python (Playwright). - A strong understanding of web scraping and UI automation. Please provide examples of your past work in Python (Playwright) along with your bid.

    €31 (Avg Bid)
    €31 licitátlag
    21 árajánlat

    ...development within VS Code. Key Tasks: - Code Debugging: I require assistance in debugging my Python code. The ideal freelancer will be able to analyze and troubleshoot my code to identify and fix any issues. - Package Installation: I'm using Django, Flask, and NumPy in my project, and I need help installing these packages correctly within my development environment. - API Integration: As part of my project, I need to integrate several APIs into my Python code. The successful freelancer will be able to guide me on how to implement these integrations effectively. Python Version: - I'm working with Python 3.x, so experience with this version is a must. Ideal Skills and Experience: - Strong Python development skills - Experience with Django, ...

    €8 / hr (Avg Bid)
    €8 / hr licitátlag
    31 árajánlat
    C# Code: Text File Data Processing 6 nap left
    HITELESÍTETT

    I have a C# code that's currently designed for file manipulation but I really need it to work like Powershell for data processing. - Task: I'm specifically working with text files and need to perform a hashing operation on them. - The end goal: The code needs to be able to read through the text files and hash them in a way that's similar to what one can do with Powershell. The ideal freelancer for this job should have: - Proficiency in C# programming, especially in the context of data processing. - A good understanding of hash functions and how to implement them in a C# code. - Familiarity with text file handling in C# is a plus. I'm looking for an efficient and smooth solution that's able to process large text files quickly. Your experi...

    €44 (Avg Bid)
    €44 licitátlag
    23 árajánlat

    Please read before off...familiar with the nuances of the APACHE, LINLUX & UBUNTU platform. The website is located DIRECTLY ON SERVER, NOT USING C-PANEL, as c-panel does not work on Ubuntu 18/20.04 You must also be familiar with HMTL5 and TPL & LINLUX You MUST have previous experience and knowledge in APACHE, LINLUX & UBUNTU OS Freelancers interested in this project should have extensive experience working with open-source operating systems and in-depth knowledge of cutting-edge SEO strategies. To be considered for this job, please include samples of your past work in your application. I'm eager to see evidence of your expertise and results you've achieved for previous clients. Your demonstrated understanding of both the tech involved and the late...

    €1040 (Avg Bid)
    €1040 licitátlag
    39 árajánlat

    I need a skilled Android developer to update my existing Android app's code to generate a signed APK for submission on Playstore. Key requirements: - The current version of the app is not specified, but I need the code to be updated to the latest standards. - The task is focused on code improvements and updating; there are no specific changes or enhancements to be made to the app's UI/UX, resolving bugs, or adding new features. Ideal Skills: - Proficiency in Java and Android Studio. - Experience with app updates on Google Playstore. - Ability to efficiently navigate and modify existing code. - Capability to generate a signed APK. This is a straightforward task for an experienced Android developer. I look forward to receiving your bids.

    €13 (Avg Bid)
    €13 licitátlag
    14 árajánlat

    I'm looking for an expert skilled in C# who can help me understand the source code of a DLL file. I'm particularly interested in an in-depth understanding of its algorithms. This task will require: - Strong knowledge and expertise in C# - Experience with DLL files - Fluency in explaining intricate algorithms The main aim isn't for debugging or enhancing functionality, but purely to comprehend how it works. Looking forward to your proposals!

    €139 (Avg Bid)
    €139 licitátlag
    16 árajánlat

    We are seeking a highly skilled Full-Stack Developer to create a Telegram channels and groups directory website from scratch. This project requires you to develop both the UI/UX design and the backend code. You will not receive any pre-existing design templates such as Figma, but you may refer to a competitor's website for inspiration. The goal is to build a platform that efficiently categorizes Telegram channels and groups by country and category, facilitating easy navigation. This website will be developed using React, Node.js, and PostgreSQL. It must be fast, secure against common web threats including SQL injections, Cross-Site Scripting, and IDOR's. It should also be optimized for search engines to achieve high visibility online. Key Features of the Website: * Cha...

    €1119 (Avg Bid)
    €1119 licitátlag
    86 árajánlat
    Debug C# MVC ASP.NET Code -- 2 6 nap left
    HITELESÍTETT

    I have a C# MVC ASP.NET Code. currently when I put a breakpoint in the code it does not stop there. i want someone to make this code debuggable. if for any reason the code does not stop at breakpoint I have that means the job is not complete Time is only 1 day, if you need more than that or you cannot do then PLEASE DO NOT APPLY I need an experienced developer to help me debug some C# MVC ASP.NET code. The client hasn't clarified if the project is for personal or business use. However, since the specifics of the debugging needed are not specified, it's expected that the code is reviewed in its entirety. Required Skills and Experience: - Proficiency in C# - MVC Frameworks - ASP.NET Core - Debugging complex applications - Systematic a...

    €24 (Avg Bid)
    €24 licitátlag
    19 árajánlat

    I am a beginner wishing to increase my knowledge and skills in live sound mixing. My priority is to learn how to effectively use portable mixing equipment, as these are what I have currently available. Ideal freelancers for this project are: - Experienced live sound mixers. - Familiar with teaching beginners. - Knowledgeable in various portable mixing equipment. I am open to different teaching methods but would appreciate practical exercises that allow me to gain hands-on experience. It's not just about theory, but also the practical execution. This is a unique opportunity for you to teach and share your expertise in live sound mixing with an eager beginner. Help me make the most of my portable mixing equipment and turn my interest in sound mixing into tangible skills.

    €83 (Avg Bid)
    €83 licitátlag
    10 árajánlat

    ...Laravel expert to optimize my website's performance, especially in terms of page loading speed and Google PageSpeed Insights score. My Laravel 10 blade code currently supports the following functionalities: - User authentication - Database integration - API integration The Core Web Vitals that need improvement are: - Excessive Dom - Largest Contentful Paint (LCP) - First Input Delay (FID) - Cumulative Layout Shift (CLS) - First Contentful Paint A critical aspect requiring attention is that the fixed menu across the site should not reload with every page change. Skills and experience required: - Proven track record in Laravel10 blade code performance enhancement - In-depth understanding and experience addressing Google PageSpeed and Core Web Vitals issues - Pr...

    €144 (Avg Bid)
    €144 licitátlag
    121 árajánlat

    I'm looking for freelancers who can help me achieve 'something' with my project, valuing at ₹700. The project purpose, the main goal, and the industry have been left up to your interpretation, which will gauge your skills, creativity, and understanding. Recommended skills and experiences: - Ability to work with vague instructions - High creativity level - Excellent problem-solving skills - Broad understanding across various industries Please provide your interpretations along with your bids. The most creative and insightful interpretations will be given priority for this project.

    €9 / hr (Avg Bid)
    €9 / hr licitátlag
    11 árajánlat

    I'm seeking a knowledgeable Ecwid expert who can handle various tasks related to my online store. While I didn't specify the tasks in detail, they...Ecwid with an existing website, managing product categories, and overseeing inventory management. To bid on this project, I would appreciate if you could include: - Samples of past work, especially those related to Ecwid stores - Your Ecwid-related experience and skills - Detailed project proposals detailing how you intend to tackle the tasks I haven't specified a completion time, so I'm open to discussions about this. Please, in your bid, let me know about any potential schedules you have in mind. Looking forward to working with a professional, deadline-focused individual with an eye for detail. Prior ex...

    €84 (Avg Bid)
    €84 licitátlag
    45 árajánlat

    Update Zerodha Dashboard Code as discussed!

    €55 (Avg Bid)
    €55 licitátlag
    1 árajánlat
    PHP to python code conversion 6 nap left
    HITELESÍTETT

    I have a backend code for a pre-existing fully function website and mobile app. The backend code is currently all written in php. I need someone to convert this existing php code into fully functional python code which I can deploy.

    €207 (Avg Bid)
    €207 licitátlag
    14 árajánlat

    As a beginner in Go Lang, I'm in need of a proficien...need of a proficient tutor who can guide me in manipulating a specific Go Lang sample code. My focus areas include: - Understanding Mutex and Go routines - Working with websockts - Grasping Control Structures - Comprehending Functions and Packages The task involves: - Live screen sharing and talking in englisch or German - Debugging the existing sample code - Adding valuable features - Enhancing the overall performance of the code Ideal candidate should have a deep understanding and experience in Go Lang, appreciate patience while tutoring, and have the ability to articulate complex concepts in a simple-to-understand manner. Efficiency, patience, and excellent communication, both verbally and in code...

    €36 / hr (Avg Bid)
    Sürgős
    €36 / hr licitátlag
    9 árajánlat

    I'm in urgent need of an efficient solution to print Barcodes and QR codes directly from an existing printer. This solution will aid in the swift management of my inventory, product tracking, and ticketing procedures. Key aspects: • Barcode/QR Code Generation: I need the ability to generate a wide range of barcodes and QR codes to meet different needs. • Printer Compatibility: As I already have a barcode printer, the solution should be compatible with my existing equipment. • Fast Turnaround: The project completion is needed ASAP. Quick delivery of the solution is of essence to my operation. Ideal skills for the job would be expertise in barcode generation, understanding of inventory and ticketing systems, and familiarity with various barcode printers. Previo...

    €76 (Avg Bid)
    €76 licitátlag
    8 árajánlat

    I'm looking for a graphic designer who can recreate my company's logo. The reason for this is the original design is outdated and I would like to have the logo updated. Unfortunately, I have lost all the source files for the logo and need it to be redone. The catch is, I need the recreated logo to be an exact replica of the original. Key Points: - The logo recreation must be identical to the original logo - I don't have the source files, so the freelancer will need to create this from scratch Ideal Skills for the Job: - Proficiency in graphic design - Experience with logo recreation and restoration - Attention to detail, as the logo must be an exact match of the original - Good communication skills in order to understand and meet the project requirements.

    €57 (Avg Bid)
    Sürgős Titkos
    €57 licitátlag
    37 árajánlat

    I'm in need of a skilled developer who can convert my existing PHP backend code (for a fully functioning Social Networking website and mobile app) to Python. This Python code should be fully functional and ready to be deployed. Key Requirements: - Conversion from PHP to Python: The existing PHP code is the backbone of the current system. The successful freelancer will be responsible for translating this into Python, ensuring the functionality remains intact. - Understanding of Social Networking Platforms: As the original code is for a social networking site, familiarity with this type of platform is crucial. Ideal Skill Set: - Proficient in PHP and Python - Prior experience with code conversion

    €21 (Avg Bid)
    €21 licitátlag
    11 árajánlat

    I'm seeking a Python expert specialized in Visual Studio Code.

    €22 (Avg Bid)
    €22 licitátlag
    41 árajánlat

    ...the necessary parts for the project - Creating a detailed schematic - Designing a PCB - Generating a 3D model of the project This project requires a high level of precision and accuracy since it's intended for industrial application. Your work will be crucial in ensuring the success of the project. In terms of software, I have not made a decision on which specific software to use yet, so I'm open to your suggestions and expertise in this area. Please keep in mind that I haven't set a specific deadline for the project yet. However, I would appreciate it if you could give me an estimate of the time it would take you to complete the project. Ideal skills and experience for this job include: - Proficiency in creating schematics, PCBs and 3D models - Background i...

    €26 / hr (Avg Bid)
    €26 / hr licitátlag
    21 árajánlat

    As the owner of a bustling website, I am seeking a freelancer capable of setting up Code Canyon mobile apps on my platform. Unfortunately, the questions about the specific apps and objective weren't answered, but my overall goal is enhancing my website to better serve and engage my users. Ideal candidate should possess: - Proficiency in integrating Code Canyon mobile apps to websites. - Proven success in related projects. Expectations for the project: - Seamless integration of mobile apps, ensuring optimal compatibility between apps and website. - Proactive communication about the progress of the project. - Ability to foresee potential issues and provide appropriate solutions. This could lead to future collaborations, given the successful completion and outcome of...

    €45 (Avg Bid)
    €45 licitátlag
    34 árajánlat

    ...Developer myself, I am now in need of someone with greater experience to come in and optimize my code for efficiency, particularly in the areas of database queries and load times. Your skills and experience: • You have at least 5 years of experience in Laravel and you're familiar with Laravel 11. • You've previously developed websites using Laravel 11. • Your forte is optimizing code efficiency and database queries. • You have a strong understanding of how to improve page load times and database query speed. Your task: • Optimize my existing codes in Laravel 11, for open source project • Main areas for optimization include database queries and code efficiency • The goal is to achieve faster page load ti...

    €509 (Avg Bid)
    €509 licitátlag
    139 árajánlat
    Fortran HDF5 Code Fixing 5 nap left
    HITELESÍTETT

    Our program is hydrodynamic modelling of a body of water. It uses hdf5 to store values in a database We use fortran 08. It keeps giving an error of "Fail modulehdf5" and segmentation error. incompressible/compressible fluids (can be) woth reynolds turbulence modelling, Fvm via projection methon nd to measure the second derivative, using upward differencing method. the term eill ...water. It uses hdf5 to store values in a database We use fortran 08. It keeps giving an error of "Fail modulehdf5" and segmentation error. incompressible/compressible fluids (can be) woth reynolds turbulence modelling, Fvm via projection methon nd to measure the second derivative, using upward differencing method. the term eill be fpund was the u, v, p, reynold stress tensors, rectangular grid...

    €46 - €93
    €46 - €93
    0 árajánlat

    I am in need of a proficient web scraper or a c...of a proficient web scraper or a cyber expert with a knack for website architecture. Your task will be to download or replicate an entire website's source code. Here’s what I need: - Comprehensive extraction of the whole source code - Clean and organized presentation of the copied code - Ensuring the process doesn't harm or disrupt the targeted site Ideal Candidate Possesses: - Extensive experience in web scraping - Detailed understanding of website structures - Adeptness in using scraping tools and software - Solid ethical hacking skills Upon successful extraction, no further assistance is required with understanding or modifying the code. However, your project deliverable shoul...

    €19 (Avg Bid)
    €19 licitátlag
    10 árajánlat