Option 1:
Generally when you're first testing out an idea, you want to build a first functional prototype cheaply and quickly. The easiest way to do this would be to use existing tools that facilitate what you want to do. For instance, you could make a web-based version (which you could embed in an app too if you want) using Marketify, as described here: http://goo.gl/2kSkUm.

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Option 2:
If you want to skip straight to investing a lot of time and energy into testing the idea, then you'd want to find, or be, a developer for the platform of choice. Either iOS, Android, or React Native (both iOS and Android). Find someone that has experience in databases (would be needed for saving profiles, products, etc.), or, if possible, in marketplace type apps.

Whenever you assign them a task, break down the task into small chunks. Make the chunks as small as you can (within reason, and to the extent that your knowledge allows), and tell your devs that if any chunks seem large, that they should further break those chunks down into bite size pieces.

For instance, for the overall task of making a new webpage, _you_ might break it down as follows:
1) Set up a database
2) Make a form that takes user email, name, and phone number and adds them to database
3) Have our site send an email to everyone above the age of 50 each week

When your devs take a look at it, _they_ might further break down the third step into:
A) Set up an email service
B) Connect it to the client database
C) Figure out how to query the database for certain users
D) Have it send emails to users over 50

You can use something like Trello to assign tasks and keep track of progress. In Trello you'd set up 4 columns titled, "To Do", "Doing", "Ready for Review", "Approved" (or combine the last two into "Done"). Then pay them and track their progress.

1. Write down your business model. What will differ your marketplace from others, how you plan to monetize it.
2. Check your competitors. Write down what you like and dislike. Ask as many people you know what they think about competitors.
3. Prepare a list of features you'd like to see. Break them down into 3 groups: must have, good to have, can add later. Leave only features from the first group. Keeping costs low at early stages is a must for startups.
5. Think about the overall style your app should look like. Have several apps on your mind (can be not only marketplaces) you like.
6. Find reliable development company. How to find it is another topic, so I'm not covering it now. In a nutshell, make sure you are comfortable with their communication, pricing and approach, they should have enough references and proven track record of successfully finished projects, ready to give access to the source code and guarantee the app will be approved. Share with them the feature list you have prepared and information about desired look and feel of the app.
7. The first stage of the development process is to analyze your requirements. You should expect from your development partner: suggestions regarding the app concept, analysis of your user types, wireframes, specification. During the whole development process your collaboration is extremely important. At this stage the company of your choice usually is able to prepare more or less accurate estimate/timeframe and additional costs list (hosting, ssl certificate, etc).
8. The next step would be to prepare design. You should expect daily updates from your development partner and provide your feedback, iterating like that till design is fully up to your expectations. At this stage it's very important to know that changes in the concept won't cost much, but after the development is started making changes will mean increased cost, so it's strongly recommended to carefully plan everything before starting coding.
9. Your development partner will break down all the functionality into 1-2 week sprints and you should expect demo builds at the end of each sprint, transparency during the whole development process and regular updates.
10. You should prepare all the metadata, carefully check the final build on your device and invite a group of people for closed beta testing, this will help to see how the app will behave when there are real users. Make sure the app was properly tested for targeted amount of users (load testing).
11. Marketing is not less important than development, so I'd suggest on promoting your app at least through social media even before the final product is ready. Marketing is a huge topic, so I'm not covering it here.

At Applikey Solutions (applikeysolutions.com) we have developed numerous mobile marketplaces and I'd be glad to assist you, explaining our approach to such projects in details. Some random thoughts, related to your project:
-The app is client server so we need to carefully think about server side architecture
-We need to think about refund policy
-Probably users should be able to communicate with real time chat.
-Apple requires app owner to be able to block users, posting inappropriate content so we'll have to integrate this feature to be approved.

1. write down the whole process in-depth on both sides from sign-up to transaction
2. Find similar marketplace apps on the app store and pick one that is inline with what you are looking to build
3. Use UXpin to mock-up what you are looking to build using the other app as a guide
4. Then I'd hire and sit down with a designer and let them design it (cost $2K - $10K)
5. I'd go through a few revisions based on a) features that are missing b) user feedback (use Invisionapp for this)
6) Then I'd hire a iOS development to build the app.

Tip: spend a ton of time with the designer to build the app and make it as simple as possible; don't try to boil the ocean and/or skip steps. If you spend a lot of time in the beginning, the developer's job will be that much easier. Gigster seems to be a good place to find high quality designers and developers.

After you have the app built, the hardest part will be to actually get users and transactions. With marketplaces you need to seed/fake one side of the marketplace in the early days. If you focus on trying to attract supply AND demand from the start, you'll never be able to do one very well.

To build a marketplace mobile app you must go step-by-step. Let us look at the steps below:
1) Analyse Your Requirements: Before starting any project, the key is to establish clarity around idea you are working on and expanding into a full-fledged product. It all begins with analysing your exact requirements and see through them to determine your goals. You can run a market check and ask people in your group who might have constructive and thoughtful opinions on general expectations from marketplace app. Collect the suggestions on app vision, user types, features and interactive elements, etc. based on these, build a wire frame and specifications. For all this, you need to collaborate with a mobile app development partner for meticulous guidance and implementation of ideas.
2) Find a Talented Marketplace App Specialist: Performing every single task on your own would be way too overwhelming and exhausting. You need reliable assistance from someone who has extensive reach in the market and proven experience of creating a marketplace app. There are many online platforms where you can access suitable app development partners and easily collaborate with them. However, make sure you can feel compatible with their business model along with their communication practices, pricing structure and project approach. Take an honest look at their references and past record of relevant projects before shaking hands with them. The marketplace app specialist you hire should guarantee access to the source code and delivery of all the features and design you have proposed.
3) Define a Strong Value Proposition: Having a unique value proposition is what sets you apart from others in the similar market. Define your goals and create a value proposition that makes your ecommerce marketplace special and considerable. You can build your own niche and invent a space even in the market where such apps exist comfortably. During the phase of proposition development and ideation, you can approach your prospects with a request to share their opinions on how they would like the current marketplace apps to be and improve to deliver more value.
4) Learn from Your Competitors: The journey of building a marketplace app is incomplete if it does not incorporate achievement of nearest competitors. Keeping a sharp eye on your competition is the best way to determine strength and weaknesses to surpass them.
The following things needs to be kept in track:
I. Star features
II. Market position
III. Target audience
IV. Influential content elements
V. Customer acquisition and retention tactics
VI. Marketing and engagement activities
VII. Business proposition
5) Defining the Business Model: Like every other business, you need to weave a solid business model for building a marketplace mobile app. It is the most crucial aspect based on which your business follows the path to successful customer acquisition and revenue generation.

Devised strategically, marketplace app business model serves as a foundation for company’s performance and drives a momentum you need for consistent profitability. The central part of this business model is formed by customers who will rely on your marketplace for specific purpose. A clear business model is the one that understands every group of customers and segment them based on their varied requirements.
6) Divide the Audience into Smart Segments: The best way to approach your audience with your marketplace app is to divide them into convenient segments based on:
I. Special tastes and preferences
II. Offers and discounts in demand
III. Seasonal changes
IV. Gender-specific or age-specific group
V. Location-specific requirements
If it is related to fashion marketplace then, Men, Women and Kids
I. Budget shopping lovers
II. Young buyers
III. Mature Professionals
IV. Senior citizens
V. Frequent and casual shoppers
You can create the best personalized offers and propositions for every segment of customers and serve them the products in the way they want.
7) Building an Impactful MVP: After you have finished working on customer segmentation and market analysis, you can venture into developing an MVP (minimum viable product) for your marketplace app. For this, make the best attempt to build and integrate the most relevant features and functionalities essential to test your idea in the market. Follow the wireframe you have prepared in the earlier phase for designing the best features. Make sure that your development partner stays up to date with customer feedback and frequent iterations. To minimize the cost-driven disasters and pitfalls, it is important to take care of iterations during the development of MVP and coding process. After the success and market fitness of your marketplace MVP, you can think of expansion and scale your original product at a sensible pace.
8) Monitor the App Performance: After you have launched an MVP and before starting to focus on expansion, the vital area of concern is to check the impact of the product on the target market through analytics.
You can track the data metrics for:
I. Numbers of visitors per day/month
II. Conversion rate during the season pick
III. Location-specific engagement and sales
IV. Most visited pages
V. Repeat customer
VI. Hot/most d items
VII. Behaviour of customer segments
VIII. Total sales of products/services on marketplace

9) Monetization and Revenue Streams: Look around for how competitors charge their clients and users for availing the marketplace services and then try to mull over what you can do differently to establish an original monetization system. Start small by approaching specific customer segments and then make changes as it grows and introduce several revenue channels without compromising service commitments. Usually, a small percentage of earning is charged from both buyers and sellers for creating comprehensive and un-objectionable monetization.
10) Scale and Expand Your Marketplace: After you are confident that your marketplace app is doing well and has achieved enough crowd of users, you can move towards growth.
a) Target Multiple Platforms: If you have not released the product on most accessible and popular platforms (iOS, Android, or Windows), now is the time. To reach more users who use diverse mobile platforms, you should launch the app on those most preferred platforms.
b) Enhance the Functionality: It is a good idea to improve or revamp existing functionality or add new features to give users even more engaging experience and luxury. Interact with users and extract their needs to develop innovative features to their taste.
c) Build a Community: Add elements of storytelling and blogging to let the audience share their opinions and ideas. Such idea is mainly focused on building a larger community and creating more engagement. You can be more imaginative and organize events that capture furthermore attention from users.
d) Third-Party Integrations: This tactic always comes handy for any successful online commerce and marketplace app that thrives as users thrive. Leverage third party integrations such as payment system, GPS services, chat messages or personalized email facility are a few to consider.
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath

Certainly! Building a marketplace mobile app involves several key steps, from conceptualization to implementation. Let’s break it down:

Conceptualization and Planning:
Identify the Market Need: Understand your target audience and their pain points. What problem will your marketplace solve?
Set Clear Goals: Define specific, measurable, achievable, relevant, and time-bound (SMART) goals for your app.
Feature List: Create a comprehensive list of features your marketplace app needs. For your case, consider user profiles, listings, search, transactions, and notifications.
High-Level Overview of Structure/Classes/Interactions:
User Profiles: Both buyers and sellers should have profiles with essential information.
Listing Management: Sellers can create and manage listings (services they offer).
Search & Discoverability: Implement search functionality for buyers to find relevant services.
Transaction Process: Handle buyer requests, notifications, and payment processing.
Admin Features: Admin dashboard for managing users, listings, and transactions.
Technical Implementation:
Choose Your Tech Stack: Consider technologies like React Native (for cross-platform mobile apps), React.js/Node.js (for web), and Amazon Web Services (for backend).
Database Design: Create a schema for user profiles, listings, and transactions.
User Accounts: Implement user authentication and authorization.
Listing Search: Develop a search feature based on user preferences.
Transaction Flow: Design the process for buyer requests, seller notifications, and payment handling.
Stripe Integration: Integrate Stripe for secure payment processing.
Recommendation:
I recommend reading this detailed guide on how to build an online marketplace: https://www.cleveroad.com/blog/how-to-build-online-marketplace/. It covers essential aspects and provides valuable insights for your project.
Remember, collaboration with experienced developers and discussing your concept further can lead to successful execution. Best of luck with your marketplace app!