This content originally appeared in the MSE weekly email on 17 June 2015.

MoneySavingExpert is a colossal, info-packed site, and this week we make no excuses for showing off the pick of our free tools.

They can hammer down bills, nail you a bargain or shine a torch on your true outgoings and financial health. Let's open our toolbox...

1) Free Income Tax Calculator

The Income Tax Calculator shows how much tax and National Insurance should be deducted from your pay (you can also factor in student loan repayments). Also use our Tax Code Calculator to check you're paying the correct tax.

2) Free TicketySplit tool slashes train fares.

Bizarrely, buying two tickets for one journey can save large. So we built the TicketySplit tool – Colin's example explains it: "I do Derby to Banbury return. A peak day return is £90.50. But Derby to Birmingham and Birmingham to Banbury day returns, staying on the same train, come to £39.50."

3) Permanently cheap gas and electricity.

Since we launched it in 2013, over 1.6m people have joined the free Cheap Energy Club, saving an average £200 per household. It finds your top tariff, monitors it each month and alerts you when it's time to switch again. Jeni tweeted: "Just saved £305 a year switching energy through Energy Club. Thanks."

4) Grab the cheapest travel cash.

There are massive variations in rates (yesterday you could get €1,230-€1,370 changing £1,000) so TravelMoneyMax compares 40 online bureaux to find which gives most on 70ish currencies. Also see Martin's Should I buy euros now? analysis.

5) Benchmark your cheapest mortgage deal at speed.

Rates are super-low but finding your best deal is tricky, so we created a comparison which finds your best bespoke deal, for remortgages, moving home and first–time buyers. As we're nerds, we also have an Ultimate Mortgage Calculator to answer everything you want to know about your mortgage.

6) Stamp Duty Calculator – how much will you pay?

Buy a house or flat and you're likely to owe stamp duty (it's called that as the document once required a stamp). It's one of the biggest taxes, and thresholds recently changed. Our Stamp Duty Calculator shows exactly what you'll pay.

7) Free budget planner – analyse your finances.

The huge, Budget Planner answers the key financial question: do you spend more than you earn? If so, you need to change, or risk eating into savings and hitting debt hell. It analyses regular spending and one-offs incl birthdays and Christmas.

Have a play with our (MoneySaving) tools
Have a play with our (MoneySaving) tools

8) Get up to £200 for old mobiles.

'Sell your mobile' sites spray the TV with ads, but there can be enormous differences per site and handset. We devised the MobileValuer comparison to speedily find top payers. You could get £121-£201 for an iPhone 5S 16GB, £90-£170 for a Samsung Galaxy S5. Flogging a newer iPhone 6 Plus 128GB could fetch up to £445.

9) Never just apply for cards and loans – that marks your credit file. Use the free Eligibility Calculators.

The only way to know if you'll get one is to apply which leaves a footprint on your credit file. Too many, especially in a short time, can hurt future applications. So we built free Eligibility Calculators which use a soft search (you see it on your file, lenders don't) to show your acceptance odds for top deals to minimise applications. 

The free Eligibility Calculators include:
0% Balance Transfers | 0% Borrowing Cards | Cashback Credit Cards
Travel Money Cards | Poor Credit | Loans Eligibility

10) Speedily unmask hidden shopping bargains.

The Local eBay Deals Mapper, iPhone App and Android App locate bargains near you. Our Amazon Discount Finder manipulates the giant's URLs to create pages, eg, beauty 70%+ off* and TV 25%+ off*.

Zoe tweeted us: "Love the eBay app – grabbed myself a new VTech Baby Dancing Tower toy for 99p (was £40ish)."

11) Join the complaining revolution – free tool to help millions fix gripes.

Automated, free complaints system Resolver* explains your rights, drafts a complaint letter, monitors replies and escalates to ombudsmen. It works on 3,500+ firms, incl shops, banks and energy companies. 18k+ have used it since we revealed we were working with it in April, incl Michelle: "Complained about Halifax on the Fri, by Tue I'd got £90." Full Resolver information.

12) Give up that £1,750 coffee.

A £2.50 coffee doesn't seem much, but one every day adds up. Our Demotivator tool shows the true cost of whatever fix you have. Sophie learned: "According to the Demotivator tool, in the last 5 years, I've spent £1,750 on lattes. Ridiculous."