Tech resource library — Hackcache
The tools, data and building blocks worth using, what each plan actually allows, and how to keep your demo link alive until judging ends.
How to use this library
Every tool here is one we would reach for on a 48-hour project, and every limit was checked against the tool's own pages in September 2026. Limits change, so check again the week before the event.
Pick one tool per job and stay with it. Switching tools halfway through the weekend costs more time than any tool saves. If you are not sure where to start, the short answer is: an AI app builder to build, its own publish button to go live, GitHub for your code, and Canva for your deck.
Read the last section, "Keep your demo alive until results" , even if you read nothing else. Several of these tools quietly take your live link offline after a few days, and judging happens after the deadline.
Build it without code
AI app builders turn plain English into a working web app with a public link. Our guide "Your working demo in 48 hours" compares their plans and daily limits in detail. In short:
Lovable : the easiest start. The free plan gives 5 credits a day and no more than 30 in a calendar month, so do not use them all practising in October.
Bolt : 300,000 tokens a day and 1 million a month on the free plan.
v0 : $5 of credits a month and 7 messages a day on the free plan.
Replit : one published app on the free plan.
Think, plan and write
ChatGPT or Claude : for planning your idea, drafting prompts for your app builder, writing the words on your screens, and your video script. Planning in a chat assistant first saves your app builder's limited credits for building.
If you write code
Visual Studio Code : the most widely used code editor.
GitHub Copilot : AI help inside your editor. There is a free plan with a monthly allowance, and verified students get a Student plan through the GitHub Student Developer Pack .
GitHub Codespaces : a full coding environment in your browser, useful on a borrowed or slow laptop. Personal accounts get 120 core hours a month, which is about 60 hours on the smallest machine.
Put it online
If you used an AI app builder, use its own Publish button and skip this section. If you wrote code yourself:
Vercel : the easiest for most web apps. The free Hobby plan is for personal, non-commercial projects, which a hackathon entry is, and its monthly limits are generous for a demo.
Netlify : also easy, but read the limit. The free plan gives 300 credits a month, and each production deploy costs 15 credits . That is about 20 deploys a month, and when the credits run out every one of your sites is paused until the next month.
GitHub Pages : for simple sites made only of HTML, CSS and JavaScript, straight from a public repository. Sites can be up to 1 GB.
Render : for apps that need a server. Free web services go to sleep after 15 minutes without visitors , and the next visitor waits about a minute while it wakes up.
Store your data
AI app builders include a database; for example, Lovable has Lovable Cloud built in. Otherwise:
Supabase : a full database with sign-in built in. The free plan gives 500 MB of database and two active projects, and pauses a project after one week with no activity .
Firebase : Google's app platform. The free Spark plan includes Firestore with 50,000 reads and 20,000 writes a day, but not Cloud Functions or Cloud Storage, which need the pay-as-you-go plan.
Google Sheets : often enough for a demo. Many app builders can read a sheet, and your whole team can edit the data together.
Collect answers from people
Google Forms : quick surveys for your user research, with answers going straight into a sheet.
Tally : nicer-looking forms, with unlimited forms and responses on the free plan within fair use.
Design it
Figma : for sketching screens before you build. The free Starter plan gives unlimited personal drafts, but only 3 shared design files for your team.
Canva : for your pitch deck, a logo, and images for your app.
Google Fonts : fonts you can use in any project.
Icons: Lucide and Google Material Symbols are open-source icon sets.
Illustrations: unDraw illustrations can be used for commercial and non-commercial work without asking permission or giving credit.
Photos: Unsplash and Pexels photos are licensed for use in projects like yours. Never take images from a Google Image search, since most of them belong to someone.
Colours: Coolors generates colour palettes. Check your text is readable with the WebAIM contrast checker : aim for at least 4.5:1 for normal text.
Test it
Your own phone. Open the live link on a phone before anything else. Most judges will see it on one screen size you did not test on.
WAVE : paste your link and it flags accessibility problems, such as missing image descriptions and low contrast.
Lighthouse: built into Google Chrome (right-click → Inspect → Lighthouse). It scores your app's speed and accessibility and says what to fix.
Mockaroo : generates realistic sample data, up to 1,000 rows per file on the free plan. You can also ask your app builder to create sample data for you.
Building blocks for India
Share on WhatsApp
A plain link, with no code or approval needed. It is documented in WhatsApp's help centre :
https://wa.me/?text=YOUR_MESSAGE opens WhatsApp with the message filled in and lets the user choose who to send it to .
https://wa.me/91XXXXXXXXXX?text=YOUR_MESSAGE opens a chat with one number: the country code without the plus sign, then the number.
The message has to be URL-encoded, which means spaces become %20 . Your app builder does this if you ask for "a Share on WhatsApp button that sends [this text]".
Maps
Leaflet with OpenStreetMap maps: an open-source map you can put in any web app without a billing account. OpenStreetMap's tile usage policy allows normal viewing by people, which is what a demo is; it does not allow heavy or offline use.
Indian languages
Bhashini : the government's language platform, with translation, speech-to-text and text-to-speech for Indian languages. Developers register, then generate an API key from their profile. Allow time for registration before the event.
Simpler option: ask your AI app builder to write your screens in Hindi or another language directly. For a demo, that is often enough.
Government and public data
data.gov.in : India's open government data portal, with datasets to download or use through an API. Register for your own API key (it takes a minute), because the shared sample key is heavily rate-limited.
API Setu : government APIs for records such as driving licences, vehicle registration and CBSE marks. Most need approval before live use, so in a hackathon use them to design realistic sample data and to show what your app would connect to.
NPCI UPI statistics : official monthly UPI figures, useful for your problem slide on the Banking & Finance theme.
Payments
Never use real money or real account details in a hackathon demo. Show a screen that says "Payment received" and say it is simulated.
If you code and want a realistic checkout, Razorpay's Test mode works like the real thing with no real money moving. It has its own test keys, and the UPI ID success@razorpay simulates a successful payment.
Work together online
Google Docs : one shared doc for your pitch, who does what, and all your links.
Excalidraw : a whiteboard in your browser for sketching screens and running "Crazy 8s" together. It works without an account.
Calls: free Google Meet group calls with 3 or more people end at 60 minutes , while one-to-one calls can run for up to 24 hours. For long working sessions, use a WhatsApp group call or Discord , or plan to rejoin the Meet every hour.
Record and present
Recording your screen, editing and uploading your video are covered step by step in "Your working demo in 48 hours".
Deck: use the HackCache Pitch deck template in the Guides section, which you can open in Google Slides and make your own copy of.
Keep your demo alive until results
Judging happens after the submission deadline, and judges open your links then, possibly days later. A link that worked on Saturday night can be offline by the time a judge clicks it. The known traps:
Supabase pauses a free project after one week with no activity. Open your app every few days until results are announced.
Render free services sleep after 15 minutes and take about a minute to wake up. A judge may think it is broken, so add "the first load can take up to a minute" to your README and your submission description.
Netlify pauses all your sites when the month's 300 credits run out, and each production deploy costs 15. Do not redeploy dozens of times on the last night.
Replit takes a free published link down after 30 days .
Lovable, Bolt and v0 keep published links up, but do not change your live app after you submit . What a judge sees should be what you submitted.
The last check, on Saturday night and again a few days later: open every link in a private window, on a phone, and make sure it works for someone who is not signed in.
Sources for the limits in this guide
Lovable credits , Bolt pricing , v0 pricing , Replit Starter plan
Netlify credits , Vercel limits , GitHub Pages limits , Render free tier
Supabase pricing , Firebase pricing , Tally pricing , Figma plans
GitHub Codespaces billing , GitHub Copilot plans
unDraw licence , Mockaroo pricing , WebAIM contrast checker
WhatsApp click to chat , OpenStreetMap tile usage policy , Bhashini APIs , Razorpay test mode
Google Meet time limits