Show HN: In a single HTML file, an app to encourage my children to invest
202 comments
·October 30, 2025linsomniac
ashleyn
Sometimes I feel like I started investing late at 26. Already, six years into the best decade for compounding in your life. But such was the power of compounding that I had reached a substantial net worth by age 35. So even just nine years can make such a tremendous difference even into later ages. It's never too late to sock money away.
ffsm8
It remains to be seen what's going to happen over the next few decades. It's entirely possible that it'll all get wiped out (the substantial gains, not all value).
While the market was a very good bet for the last 50yrs, its not a guarantee.
Especially in the current climate you should be fully aware that it's significantly more risky to start investing today vs 10 yrs ago.
(Riskier doesn't mean it's necessarily a bad idea. It should just be a conscious decision under the acknowledgement that the upward trajectory is not certain. Especially in current political climate - and that "hodl"-ing doesn't necessarily mean you'll eventually get back what you invested, if a downturn manifests)
ashleyn
Your money has to go somewhere or it will rot to inflation. If you're ultrabearish on stocks, snap up bonds. If you're bearish on stocks and bonds alike, snap up gold. Either way, bare minimum of what to do with your money long term is to preserve its value across inflation.
But really I would recommend nonetheless staying the course with investment advice on a stocks/bonds balance relative to your age. Increasingly, the economy distributes not through labour but through capital and holding stocks is essential even with their inherent risks. Even in light of that CNN article about meme stock and crypto investors having the last laugh over the past decade, indices of ordinary large-cap stocks bring you exposure to these things.
skeeter2020
>> Especially in the current climate you should be fully aware that it's significantly more risky to start investing today vs 10 yrs ago.
First, I don't think this absolute statement is true; I think you need to look at it from the alternatives perspective. If not investing then what? bury gold? spend it all?
Second, are we at a much riskier time than past history, both short & long term? I made significant contributions in 2014, saw 30%+ wiped out within 6 months and seen it all come back and more with the power of long timeframes.
Third, investment can take a lot of forms, not just today's hot tech stocks. I won't get into it beyond the standard think long term and avoid leverage, which seems to be completely inline with start early; start now.
elictronic
I started my daughter investing with a custodial account at 13. She put a few hundred dollars of her money in and I convinced her by matching her investment and told her if the amount ever went below the original investment I would backstop any loss.
Investing is all about that long term gain and slow growth. Having 10 years of experience after finishing college will do so much more than Robinhood for refrigerators.
linsomniac
I've made a similar deal with my kids: Around 7 years ago I set up a "kid retirement" plan for them, where they couldn't touch the money until they were 18, but any money they put in I would match, and I'd also give them 10% APY with monthly compounding. My daughter aged out of it a couple years ago, she got something in the $100 range. Her brother still has a 18 months left, and I just recently rolled his over into the custodial account, he's got over a grand in there currently.
My daughter I just recently set up a ROTH for her and told her I'd match anything she puts into it, and stressed she should put something into it now from her savings, and then put some of her paycheck into it, anything is better than nothing. So far she's declined the free money. I'm going to set one up for my son, once he's at the point of having an income to justify it. She's very smart, but in some ways she's very stupid.
sureglymop
You say that now but as a young person with a decent income and no family or many responsibilities it's hard to even know where to start.
And I'm not even talking about what to invest in, I'm already confused at which platform/bank/whatever to do it through. The "meta", if you will. I just want to invest the 70% of my salary I don't need every month and not think about it for 40 years but how? Maybe an important detail, I'm from Switzerland, perhaps it's easier in the US with things like Vanguard.
Brendinooo
My understanding is that, if the market generally continues on the rate of return it's averaged throughout its history (that is, if you're not a doomer), then the single most important thing is showing up to play.
People who try to time the market or wait for a perfect time or pick the exact right blend of stocks, on average, don't do as well as people who pick a boring index or mutual fund and forget about it for 40 years.
linsomniac
Yes, however: My father in law gave me some great advice: Pick a stock or two and put some small amount of your investments into it, like 1-5%. This makes the investing more fun. And he was very right, not the least of which because the stock I put $7K in exploded and ended up worth over $200K. ;-)
My BIL put money into Underarmor (he's an outdoors guy) and Electronic Arts (he's also a gamer), both of which have done good for him. My son put some money into Roblox (he's a gamer), and that's done well also.
coldpie
Don't know about Switzerland, but most US brokers offer some kind of "target retirement date" fund, which automatically shifts from higher-risk assets to lower-risk as you approach retirement. VFIFX is one from Vanguard, for example. Pick one you like (just ask a coworker what they use, if you pick a big-name brokerage it really doesn't matter which one), shove your extra cash into it regularly, and forget about it. Then cross your fingers the market isn't actively crashing when you plan to retire (this is unlikely, but it does happen a couple times per century).
If you start to get into truly high wealth amounts (USD$500K+) you might consider hiring a wealth advisor, who can probably do better even after accounting for their fees.
koakuma-chan
Even when it crashes it's like 20% no? It's not actually that big of a deal.
mchr3k
All the choices you have to make can be very daunting. I was very lucky to have a colleague at work who gave a talk at the right time in my life with some plausibly right choices.
In the UK I started out using https://www.charles-stanley-direct.co.uk/ and later moved to https://www.ii.co.uk/. I initially invested in https://www.vanguardinvestor.co.uk/investments/vanguard-life... which is a fund which is available on a bunch of platforms. These days I recommend https://www.vanguardinvestor.co.uk/ to some people as an easy and low fee way of getting started with Vanguard funds in the UK.
I don't know what the best trading platform options are in Switzerland - it looks like all of the ones I'm familiar with are not relevant to you.
The key thing is you want to minimise two types of fees: * Platform fees * Product fees
For example Charles Stanley Direct charge 0.3% platform fees, and https://www.vanguardinvestor.co.uk/ charges 0.15% platform fees.
Vanguard LifeStrategy® 100% Equity Fund charges 0.22%.
The bottom line is that there are lots of good choices, and the main thing is to make a choice and get started. You can always optimise/improve your choices later.
singiamtel
I'm also in Switzerland, currently my approach is to invest in Vanguard VOO (tracks the S&P500) via Interactive Brokers. There is a way to setup auto transfer and invest every month
As a caveat your money will be in dollars and in American companies, which might not be what you want, but it's worked for me well so far
whoooboyy
Read "The Four Pillars of Investing". Basically index funds, diverse whole markets, leave it alone and watch it grow.
I did this at 22, and that seed money has grown a ton.
koakuma-chan
Your bank probably has an investment platform, you can just use it, it doesn't matter. My portfolio is 70% XEQT 30% CASH.TO—don't bother with anything else.
onli
Oh, that can be bad advice. It does matter a lot if the bank asks for high fees, which would be the case with all(?) German banks, and I'd be surprised if that's different in Switzerland.
onli
For the plattforms, that also blocked me for a while. But it is easy now. You just get one account at a platform that offers a free broker account and supports buying the etf you want without extra fees.
Typical options in Europe: Trade Republic, scalable, Consors Bank.
Then the usual: Around 10K where you can access it directly, a small amount in an investment with percentage (scalable and trade republic both offer that, limit there is or was 50k), rest in one broad ETF like one that follows the FTSE all world (vanguard or invesco offer that, one is bigger, the other asks for less fees).
No affiliation, and I dont know whether being outside of the EU changes things. And yes, there is the risk that we are in a huge bubble now and it popping would at first significantly lower the money put into the etf. But you certainly do have access to vanguard etc.
Have a look now and at the latest this weekend you have this solved, hopefully forever.
nxor
Retirement is not mentioned in the post
ikamm
It is one of the most common reasons people invest though so it's entirely relevant
koakuma-chan
I don't think you need a reason to invest. You should be making more money than you spend, so you might as well put the surplus to work.
ericyd
Financial literacy is a gift, and absolutely omitted from standard education, which is unfortunate.
That said, I don't think knowledge of investment gets you very far if your job pays subsistence wages. I worked for a popular fintech focused on personal investment and their narrative was essentially "financial freedom through investment". I think it's important to understand that even the most sophisticated knowledge of investment and personal finance does nothing substantial if you aren't making surplus money to begin with.
bilekas
> Financial literacy is a gift, and absolutely omitted from standard education, which is unfortunate.
With my tinfoil hat on, I feel like that is by design.
tinfoilhatter
I don't think you even need to wear a tinfoil hat to reach this conclusion. Knowing about the origins of the modern outcome-based education systems in the West (we borrowed from the Prussian education system which replaced the classical education system based on the Trivium and Quadrivium) I would assert that your claim is spot on.
internet_points
you should know haha :)
alxmdev
Probably, because everything would collapse if everyone was an "investor" and fewer people did actual work to keep the world going.
koakuma-chan
There are people who don't invest? Do they just keep their retirement savings in cash? I imagine for most people either the government or their employer invests for them.
RealStickman_
This type of investing isn't about day trading following the latest hype. It's about putting some surplus money to better use for when you need it in 10-20 years.
nxor
How couldn't it be? If the finance industry made things clearer then more people would benefit from it.
triceratops
I don't know what you mean by that. They teach compound interest in every school. Basic economics too. Anything more advanced is going to be lost on most kids, because that's most adults' level of financial literacy too.
The problem is many kids don't have much money to save or invest. Or if they do, real banks kinda suck when you only have a kid amount of money ("Here's the 0.2% interest on your $37 balance"). So they can't apply what they learned. An app like this, backed by the Bank of Mom and Dad, is great for practice.
danielbarla
While I certainly had the _concept_ of compound interest taught to me at some abstract mathematical level, the application to real life practical financial scenarios was definitely not done [1]. Economics as a whole was an optional subject.
I think schools and curriculums could do a whole lot better in representing this important facet of life. More broadly, I often feel that "applying all that math you've learned to real things" is a subject that could be taught.
[1] Seriously, having applied math questions like "Johnny earns X per year, with a cost of living of Y. Assuming inflation of Z and average yearly returns of R, what percentage should he be putting away, starting at age 25, so that at age 50 he essentially gets the equivalent of his own salary each month?" would likely cause some lightbulbs to go off in the kids' heads.
triceratops
> the application to real life practical financial scenarios was definitely not done
Of course it was. You can't teach compound interest without referring to money or banks. That's the whole point of it. Otherwise it's just multiplication.
seemaze
> that's most adults' level of financial literacy too.
The vicious cycle! We have to start somewhere..
recursive
Where do you send your money to invest? What is a stock? This is the type of information missing.
triceratops
> Where do you send your money to invest?
If they had taught you that in high school 10 or 20 years years ago, it would be outdated by now. People used to save in savings accounts. Then 401ks. Then individual brokerage accounts with index funds. Now crypto or whatever is hot using some fintech app.
> What is a stock?
That's fair. It can come up in basic economics but not always.
skeeter2020
investment for many is more important than ever, because with home ownership out of reach younger people those with any savings are looking for alternatives. I just hope that - much like how you wouldn't buy and sell your house every day - they can resist the urge to be overly active investors.
nxor
Sure but if you learn a lot about investing then surely you have learned a lot about other stuff too and maybe have chances at a good job. Not that I disagree
johntiror
There’s an old story about Rothschild getting a haircut when the barber started giving him stock tips. Rothschild thanked him, left the shop, and immediately sold all his holdings. The reason was: “When even the barber is investing, the market’s gone too far.”
I might be wrong, but reading this, I couldn’t help but think: if we’ve reached the point where we’re building apps to get our kids into investing, maybe we’re living through our own “barber moment.”
vslira
The reasonable interpretation of such a project is not to pump the stock market even higher by getting children to invest their savings into it, but to inculcate the habits of investing over time so they can do it properly as adults.
I'm sure Mr. Rothschild would be fine with this learning tool.
tinfoilhatter
The Rothschild bloodline is responsible for helping to orchestrate every modern war since the Napoleonic Wars, by loaning money to both sides of the conflict. Major General Smedley D. Butler wrote about this in War is a Racket. I personally, don't give a damn what Mr. Rothschild would be fine with, or the rest of his disgusting family.
random9749832
Narrative: You are teaching about the intricacies of finance and the stock market.
Reality: Dump everything into Nvidia / S&P 500. Number go up.
kccqzy
In December 2017 I literally saw shopkeepers and barbers checking Coinbase every few minutes when they weren't with customers. I sold a substantial portion shortly afterwards. Of course I'd be much richer today if I hadn't done that. But I don't really regret it because it's not real investing; it's speculation.
projektfu
It's certainly apocryphal and you have the British version, probably. In the US it is usually Joe Kennedy and a shoeshine boy, and also didn't likely happen. These stories are useful parables, and they serve the purpose of explaining why the smart money didn't get cleaned out when the rubes did.
Still, if a 10 year old had started investing 10% in the market in 1920 and stuck through it during the depression, even with no income coming in at the time, they would have done handsomely through the recovery and into old age. In fact, a middle aged person who had been investing until 1929 would have not been fully cleaned out, and that money would have recovered its value by 1943. Margin was what killed fortunes in the day, so the lesson to learn is to avoid margin for your investment portfolio. (Speculation is a different story).
sd8f9iu
I think the assumption here is the investment vehicle will be large bundles of diverse stocks, e.g. via a mutual fund or equivalent ETF. That's the standard way to invest 401Ks and other savings, and something for which stock tips are no use.
taude
The market's are different now. Everyone's 401K plans are automatically investing in them each month (my theory on why equities are so expensive now).
david927
Different as in much worse? It's not that you're wrong but, just to be clear, the problem with investing as the only place to keep up with inflation means that markets will detach from value, and become a giant Ponzi scheme.
There is no such thing as "growth detached from value" lasting forever.
random9749832
Greed is at a 21st century high. I am just waiting for the rugpull moment when billionaires decide the show is over (https://seekingalpha.com/news/4464647-deeper-dive-the-wealth...).
Even George Hotz understands this is the symptom of a larger issue and it is going to end bad: https://geohot.github.io/blog/jekyll/update/2025/10/24/gambl...
koakuma-chan
What is going to happen specifically when billionaires decide the show is over?
freitzzz
Hi, sorry to be that guys, I just wanted to make some corrections on what you call your app a "plain html file". Your HTML file loads:
- react app - pwa manifest - tailwind css
This is not at all a "plain html" file.
mrweasel
One small html file, and half a megabyte of CSS and Javascript framework... oh and the html file contains 800 lines of additional Javascript.
dangus
I bet $10 that it’s vibecoded, and it’s such a dirt simple calculator that perhaps it was even done with a single prompt.
The AI just picked react because that’s the most common framework.
mavamaarten
That's the first thing I thought when opening it. Sure looks like a "make me an app" response that Claude would output.
I mean nothing wrong with that, I needed a silly calculator thingimabob too yesterday (for some CRC checks on a piece of text) and Claude quickly cooked something up for me.
But I'm not writing blog posts about it, releasing the tool in the wild, and claiming I wrote it. Blegh.
brazukadev
is plain html different from single HTML? Because it is a single HTML that you can "Save as" and have one html with the working app.
freitzzz
In my opinion this can't even be labeled as a single HTML file, because it loads external files to complete the app. But back to the question, a "plain html" file doesn't load any external resources and is usually semantically described.
davsti4
Agreed - which is disappointing.
My firewall shows blocked connections to cdn.tailwindcss.com and unpkg.com
vultour
I have a "plain Python file" that only imports TensorFlow.
bossyTeacher
When people talk about a single plain HTML file, it implies that all markup and code is contained in the file and no libraries are being used
croes
If you can run the app without any other files and without internet then it’s plain and a single file.
mpalmer
[flagged]
andrepd
It's a valid point lol. "A single html file" for me is a Ciechanowski page, not something that needs many gigabytes of bloat to compile.
taude
You are that guy. It was obvious that he built some interactive app packaged in a single html file. There's going to be javascript and stuff in there...doah.
EDIT: I wouldn't have expected external dependencies, though.
Waterluvian
I had a very similar idea this summer. But my kids are 6 and 8, so I approached it using the video game approach. It's been an absolute smash hit and entirely altered the habits of doing chores in this home. It's been about 3 months and it's still going stronger than ever. The whole thing is a static page, driven by a Google Spreadsheet that Mom and I edit to adjust goals and track progress.
https://ibb.co/RTw5sCDJ https://ibb.co/ycRB8750 https://ibb.co/gLGQ0tKT
roberdam
great!, mobile app?
Waterluvian
It’s just a static hosted page they run on the family iPad. There’s no server at all!
I should really clean it up and make a blog post about it. But wanted to share it here because this project reminded me of it :)
thw_9a83c
Nice! I also created a "virtual bank account" for my kids when they were 7-8yo. They can choose to take the weekly cash or put it in their savings account. My bank gives them a 5% interest rate per month, which isn't bad. Explaining the idea of compound interest this way is easy.
However, I think that's the easier part of being an investor. The more complicated part is risk management. With a savings account, there is basically zero risk. But that's not how you invest these days.
mattmanser
5% per month? Where is this crazy money generator? Assume you meant per year here!
It's not zero risk:
- Your currency may collapse, see Germany 1930s, Argentina, Zimbabwe, Venezula, etc.
- Only a certain figure is protected in savings, though governments will act aggressively to protect that (see 2008 + the Icelandic/UK/Dutch palava)
Galanwe
> I act as their investment agent, assigning realistic interest rates
Author then proceeds to put 15% annual interest rate...
roberdam
11% is a safe interest rate on my country (py), I just got a 14.5% offer for local bonds BBB+
mlok
py = Paraguay, for those like me who didn't know
wara23arish
stay vigilant Lebanon was granting 12% rates and everything was fine and “covered” by central bank until it wasnt
Galanwe
> 11% is a safe interest rate on my country
11% may be the safest bond you have access to, but that doesn't make it _safe_ in absolute terms.
roberdam
up to 30k, cover 100% by the central bank
Jommi
the issue is your local currency will lose its value over time
triceratops
Is there a (government-issued) currency that doesn't?
meatjuice
I can feel the vibe-coding "vibe" from every vibe-coded websites, somehow.
nxor
M dashes everywhere, bold text everywhere ... what's next, teaching them to over-rely on LLM's? And if we're teaching them about investing, can we also teach them about the ethics of investing? As in, employing a bunch of people to direct the profit of their work into the hands of investors?
LandR
Will they also have periods of a bear market and see their money go down ?
roberdam
hopefully, “The first national bank of dad” remains solvent.
patapong
And can they take loans with negotiated interest rates and lock-in periods? Or invest in more risky products such as derivatives with a corresponding chance to lose all money? So much potential... ;)
ozim
First they have to fill in KYC questionnaire and have no risky products if they did not have investing experience.
roberdam
unlimited apps ideas :D
pmg102
You're giving a 15% growth rate with zero volatility? That isn't going to teach many important lessons.
How about offering a range of rates with volatility increasing as rate increases. Then they can think about the benefit of guaranteed return vs the benefit of long-term growth, or a combination of both.
yaky
Be careful with comparing real-life things and experiences with a (virtual) number on a screen, especially for children.
I used to know an adult who only cared about that number going up, despite making more than a comfortable amount of money. Live with parents, save on rent/mortgage, number goes up faster. Buy cheapest food, take leftovers from work-catered lunches, number goes up faster. Scam your way into being hired for a position you are severely underqualified for, get terminated after three months, keep the salary and sign-on bonus, number goes up. Invest pretty much everything (because there are almost no expenses), compound interest.
ericyd
This feels like a severe anecdotal example which I'm not sure applies to most people.
ct0
Agreed, in 7th grade we did a stock market simulation, it made winning feel too easy.
nxor
Ahah but green ticker good red ticker bad. What's the problem sir
There's an awful lot of negativity here, but as someone who's 55 and has earned a good wage since I was 17, I really wish I had taken investing more seriously from the very beginning. While I knew of compound interest, I really didn't understand it until like a decade ago. If I'd started putting 5% of my money into a target retirement plan from 17, I'd be retired now. As it is I'm not doing badly, but I really wish I'd started earlier.
So I say: Good on you.
Somewhat related: I just got my son set up with a custodial account and put his "kid retirement" plan into it, and let him pick a couple stocks to put some money into, and put the majority of it into target retirement and a few stocks and EFTs, so he can get some ideas of how they perform, make it a little fun with picking things he's into, and also follow ups and downs of the market, all of which I think is good education.